# Problem with chtMultiregionFoam radiation boundary condition

 Register Blogs Members List Search Today's Posts Mark Forums Read

 August 19, 2015, 05:48 Problem with chtMultiregionFoam radiation boundary condition #1 Member   baran Join Date: Aug 2014 Posts: 45 Rep Power: 11 Greeting all!!! I have a simple case as follows...in OF 2.4 1. Cavity with heater inside 2. Surrounding this cavity some insulation is there So I run the radiation case(with view factor model) in chtMultiregionFoam(transient) with interface boundary condition of solid and air.. Code: ```type compressible::turbulentTemperatureCoupledBaffleMixed; value uniform 300; Tnbr T; kappa fluidThermo; kappaName none;``` Fluid thermo property is tutorial one. It is run completely okay and I run it for around 360 sec then stop that one.Log file after 360 sec is like this... Code: ```Region: fluid Courant Number mean: 0.009927002 max: 0.29967996 Region: fibrothal_in Diffusion Number mean: 5.0662336e-08 max: 3.0645162e-07 Region: solid_bricks Diffusion Number mean: 3.3063735e-08 max: 1.7757998e-07 Region: unifrax_out Diffusion Number mean: 1.0011137e-07 max: 3.0843423e-07 deltaT = 0.0010946195 Time = 356.6388 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00025637481, Final residual = 4.407068e-09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00027934907, Final residual = 9.510753e-09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.0002301347, Final residual = 1.7324477e-09, No Iterations 2 DILUPBiCG: Solving for h, Initial residual = 3.1476392e-05, Final residual = 7.3471181e-08, No Iterations 1 Min/max T:313.58391 1118 GAMG: Solving for p_rgh, Initial residual = 8.5854497e-05, Final residual = 9.4845113e-08, No Iterations 7 GAMG: Solving for p_rgh, Initial residual = 3.5173418e-06, Final residual = 5.4325282e-08, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 8.6238562e-07, Final residual = 3.8513529e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 6.074565e-10, global = 6.3652211e-13, cumulative = -2.197283e-07 GAMG: Solving for p_rgh, Initial residual = 1.0315776e-06, Final residual = 3.9160376e-08, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 1.669925e-07, Final residual = 2.9482081e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 6.8532497e-08, Final residual = 6.8532497e-08, No Iterations 0 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 1.080931e-09, global = -4.0250703e-14, cumulative = -2.1972834e-07 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 1.2940158e-06, Final residual = 1.3251284e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.7071703e-12, Final residual = 1.7071703e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 640.55258 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 1.0267441e-06, Final residual = 4.8127074e-13, No Iterations 1 DICPCG: Solving for h, Initial residual = 8.4350547e-13, Final residual = 8.4350547e-13, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 458.84315 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 9.9373252e-07, Final residual = 9.9373252e-07, No Iterations 0 DICPCG: Solving for h, Initial residual = 9.9373252e-07, Final residual = 9.9373252e-07, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 303.89972 ExecutionTime = 133423.49 s ClockTime = 136999 s Region: fluid Courant Number mean: 0.0099269187 max: 0.29966461 Region: fibrothal_in Diffusion Number mean: 5.0662347e-08 max: 3.0645172e-07 Region: solid_bricks Diffusion Number mean: 3.3063735e-08 max: 1.7757998e-07 Region: unifrax_out Diffusion Number mean: 1.0011137e-07 max: 3.0843423e-07 deltaT = 0.0010946195 Time = 356.6399 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00025636135, Final residual = 4.3780302e-09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00027935499, Final residual = 1.0088861e-08, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.00023013524, Final residual = 1.6871542e-09, No Iterations 2 DILUPBiCG: Solving for h, Initial residual = 3.1473979e-05, Final residual = 7.3570805e-08, No Iterations 1 Min/max T:313.58441 1118 GAMG: Solving for p_rgh, Initial residual = 8.5834205e-05, Final residual = 9.5254497e-08, No Iterations 7 GAMG: Solving for p_rgh, Initial residual = 3.5163029e-06, Final residual = 5.4570072e-08, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 8.6202952e-07, Final residual = 3.8610652e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 6.0899296e-10, global = 6.481879e-13, cumulative = -2.1972769e-07 GAMG: Solving for p_rgh, Initial residual = 1.0315463e-06, Final residual = 3.9050125e-08, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 1.6693103e-07, Final residual = 2.9416253e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 6.8558156e-08, Final residual = 6.8558156e-08, No Iterations 0 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 1.081336e-09, global = -3.652917e-14, cumulative = -2.1972773e-07 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 1.2940145e-06, Final residual = 1.3250951e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.7071583e-12, Final residual = 1.7071583e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 640.55404 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 1.0267414e-06, Final residual = 4.812706e-13, No Iterations 1 DICPCG: Solving for h, Initial residual = 8.4350791e-13, Final residual = 8.4350791e-13, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 458.84273 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 9.9373296e-07, Final residual = 9.9373296e-07, No Iterations 0 DICPCG: Solving for h, Initial residual = 9.9373296e-07, Final residual = 9.9373296e-07, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 303.89975 ExecutionTime = 133424 s ClockTime = 137000 s``` Then i changed the boundary condition of fluid and solid interface .. Code: ``` type compressible::turbulentTemperatureRadCoupledMixed; value uniform 300; Tnbr T; kappa fluidThermo; QrNbr none; Qr Qr; kappaName none;``` fvSolution of air is as follows... Code: ```solvers { rho { solver PCG; preconditioner DIC; tolerance 1e-7; relTol 0; } rhoFinal { \$rho; tolerance 1e-7; relTol 0; } p_rgh { solver GAMG; tolerance 1e-7; relTol 0; smoother GaussSeidel; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; } p_rghFinal { \$p_rgh; tolerance 1e-7; relTol 0; } "(U|h|k|omega|epsilon|R)" { solver PBiCG; preconditioner DILU; tolerance 1e-7; relTol 0.1; } "(U|h|k|omega|epsilon|R)Final" { \$U; tolerance 1e-7; relTol 0; } } PIMPLE { momentumPredictor on; nCorrectors 2; nNonOrthogonalCorrectors 2; } relaxationFactors { fields { rho 0.1; p_rgh 0.1; } equations { "h.*" 0.1; "U.*" 0.1; "(k|epsilon|R)" 0.1; G 0.1; "ILambda.*" 0.1; Qr 0.1; } }``` fvScheme of air air is as follows... Code: ```ddtSchemes { default Euler; } gradSchemes { default cellLimited Gauss linear 1; // Gauss linear; } divSchemes { default none; div(phi,U) Gauss upwind; div(phi,k) Gauss upwind; div(phi,K) Gauss linear; // Gauss upwind; div(phi,epsilon) Gauss upwind; div(phi,h) Gauss upwind; div(phi,omega) Gauss upwind; div(phi,R) Gauss upwind; div(R) Gauss linear; div(Ji,Ii_h) Gauss linearUpwind grad(U); div((muEff*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default none; laplacian(rhorAUf,p_rgh) Gauss linear limited 0.333; laplacian(muEff,U) Gauss linear limited 0.333; laplacian((rho*(1|A(U))),p_rgh) Gauss linear limited 0.333; laplacian(alphaEff,h) Gauss linear limited 0.333; laplacian(DepsilonEff,epsilon) Gauss linear limited 0.333; laplacian(DkEff,k) Gauss linear limited 0.333; laplacian(DomegaEff,omega) Gauss linear limited 0.333; laplacian(DREff,R) Gauss linear limited 0.333; laplacian(gammaRad,G) Gauss linear limited 0.333; } interpolationSchemes { default linear; } snGradSchemes { default limited 0.333; } fluxRequired { default no; p_rgh; }``` Initially it is running well but after some iteration it is giving negative value of T in fluid zone ,then it is diverged.....showing Code: `Maximum numbers of iterations exceeded` It is giving in practical results..... Apart from this bc remaining thing is same for two cases...Is there is a problem with this boundary condition..?? Please suggest something...

August 20, 2015, 09:29
#3
Member

baran
Join Date: Aug 2014
Posts: 45
Rep Power: 11
This is the log file of that case....from where it is started diverging...
Quote:
 Region: fibrothal_in Diffusion Number mean: 3.7268416e-08 max: 2.2962241e-07 Region: solid_bricks Diffusion Number mean: 2.512897e-08 max: 1.3494945e-07 Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07 deltaT = 0.00083183564 Time = 73.539995 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 6.7636734e-05, Final residual = 1.3441408e-08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 4.6392292e-05, Final residual = 1.0721153e-08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 6.0782809e-05, Final residual = 8.146975e-09, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 1.4442565e-05, Final residual = 1.5485771e-09, No Iterations 1 Min/max T:302.35042 796 GAMG: Solving for p_rgh, Initial residual = 0.0056481889, Final residual = 8.1606344e-08, No Iterations 7 GAMG: Solving for p_rgh, Initial residual = 4.0515088e-06, Final residual = 4.6215754e-08, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 9.1679808e-07, Final residual = 3.0994507e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 1.4519277e-11, global = 7.237251e-13, cumulative = 4.4382842e-08 GAMG: Solving for p_rgh, Initial residual = 3.9095027e-07, Final residual = 4.9657638e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 1.3685112e-07, Final residual = 2.4273418e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 5.9664268e-08, Final residual = 5.9664268e-08, No Iterations 0 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 2.7949542e-11, global = 4.6906331e-13, cumulative = 4.4383311e-08 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 7.0222902e-06, Final residual = 4.4745359e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 4.8146941e-12, Final residual = 4.8146941e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 654.37783 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 5.3096873e-06, Final residual = 1.9608229e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 3.6329413e-12, Final residual = 3.6329413e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 691.02751 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 3.415013e-06, Final residual = 3.0740924e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 3.1231553e-12, Final residual = 3.1231553e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 302.19046 ExecutionTime = 25647.98 s ClockTime = 26270 s Region: fluid Courant Number mean: 0.01846859 max: 0.29994596 Region: fibrothal_in Diffusion Number mean: 3.7268432e-08 max: 2.2962282e-07 Region: solid_bricks Diffusion Number mean: 2.5128969e-08 max: 1.3494945e-07 Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07 deltaT = 0.00083183564 Time = 73.540827 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 6.7630737e-05, Final residual = 1.3418181e-08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 4.6370261e-05, Final residual = 1.0742627e-08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 6.0847475e-05, Final residual = 8.1523053e-09, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 1.4442106e-05, Final residual = 1.5490886e-09, No Iterations 1 LU Back substitute C matrix.. Min/max T:302.35057 796 GAMG: Solving for p_rgh, Initial residual = 0.0056481019, Final residual = 7.6797676e-08, No Iterations 7 GAMG: Solving for p_rgh, Initial residual = 3.857246e-06, Final residual = 9.7154467e-08, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 8.8653178e-07, Final residual = 3.3270662e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 1.5585688e-11, global = -4.472e-13, cumulative = 4.4382864e-08 GAMG: Solving for p_rgh, Initial residual = 3.7940167e-07, Final residual = 4.9666952e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 1.3330598e-07, Final residual = 2.477867e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 5.9175294e-08, Final residual = 5.9175294e-08, No Iterations 0 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 2.7720599e-11, global = -2.3320649e-13, cumulative = 4.4382631e-08 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 7.0243905e-06, Final residual = 4.4725576e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 2.4377613e-11, Final residual = 2.4377613e-11, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 654.37063 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 5.2875841e-06, Final residual = 1.9709967e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 2.8414773e-09, Final residual = 2.8414773e-09, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 295.48786 max(T) [0 0 0 1 0 0 0] 741.78106 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 3.4149741e-06, Final residual = 3.0740581e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 3.1189356e-12, Final residual = 3.1189356e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 302.19047 ExecutionTime = 25648.68 s ClockTime = 26271 s Region: fluid Courant Number mean: 0.018468399 max: 0.29995557 Region: fibrothal_in Diffusion Number mean: 3.7268448e-08 max: 2.2962323e-07 Region: solid_bricks Diffusion Number mean: 2.5128969e-08 max: 1.3494945e-07 Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07 deltaT = 0.00083183564 Time = 73.541659 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 6.7625913e-05, Final residual = 1.3402331e-08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 4.6344566e-05, Final residual = 1.0754375e-08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 6.0932861e-05, Final residual = 8.1687571e-09, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 1.4447945e-05, Final residual = 1.5504852e-09, No Iterations 1 Min/max T:292.46006 796 GAMG: Solving for p_rgh, Initial residual = 0.0056581752, Final residual = 7.6764428e-08, No Iterations 12 GAMG: Solving for p_rgh, Initial residual = 2.2938121e-05, Final residual = 5.568475e-08, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 4.8180826e-06, Final residual = 4.5585251e-08, No Iterations 3 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 2.1354346e-11, global = -1.0446098e-12, cumulative = 4.4381586e-08 GAMG: Solving for p_rgh, Initial residual = 1.7763567e-06, Final residual = 4.7846782e-08, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 5.9132237e-07, Final residual = 5.9130769e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 2.4540226e-07, Final residual = 3.1298447e-08, No Iterations 1 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 1.4662065e-11, global = -6.7971007e-14, cumulative = 4.4381518e-08 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 7.0245586e-06, Final residual = 4.4724421e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 9.1267502e-12, Final residual = 9.1267502e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 654.37584 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 5.2888596e-06, Final residual = 1.9709382e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 8.289224e-11, Final residual = 8.289224e-11, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 292.46034 max(T) [0 0 0 1 0 0 0] 661.85799 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 3.4149352e-06, Final residual = 3.0740239e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 3.127232e-12, Final residual = 3.127232e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 302.19048 ExecutionTime = 25649.12 s ClockTime = 26271 s Region: fluid Courant Number mean: 0.018468212 max: 0.29996512 Region: fibrothal_in Diffusion Number mean: 3.7268464e-08 max: 2.2962363e-07 Region: solid_bricks Diffusion Number mean: 2.5128969e-08 max: 1.3494945e-07 Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07 deltaT = 0.00083183564 Time = 73.54249 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 6.7947711e-05, Final residual = 1.4502077e-08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 4.6627109e-05, Final residual = 1.1456384e-08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 6.1359507e-05, Final residual = 7.2212648e-09, No Iterations 1 DILUPBiCG: Solving for h, Initial residual = 1.4447972e-05, Final residual = 1.5510617e-09, No Iterations 1 Min/max T:292.4726 796 GAMG: Solving for p_rgh, Initial residual = 0.0056490789, Final residual = 8.349077e-08, No Iterations 10 GAMG: Solving for p_rgh, Initial residual = 1.4609603e-05, Final residual = 6.3234719e-08, No Iterations 4 GAMG: Solving for p_rgh, Initial residual = 3.3731476e-06, Final residual = 8.6407996e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 4.0477576e-11, global = 2.3788157e-14, cumulative = 4.4381542e-08 GAMG: Solving for p_rgh, Initial residual = 1.3010508e-06, Final residual = 4.1176202e-08, No Iterations 2

Last edited by baran_foam; August 20, 2015 at 09:30. Reason: modify

 August 20, 2015, 14:30 #4 Retired Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,975 Blog Entries: 45 Rep Power: 128 Greetings to all! @baran_foam: Since you sent me a PM and I spent some time trying to imagine/diagnose this issue, my best guess is that there is no heat being released by the region "solid_bricks", which is why it ends up overheating and crashing the simulation, because the temperature range falls out of the working range of the polynomials for the material properties. Beyond that, you should follow Alex's suggestion, specially the one about looking at the results in ParaView. Best regards, Bruno __________________ OpenFOAM: FAQ | Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

 August 24, 2015, 01:17 #5 Member   baran Join Date: Aug 2014 Posts: 45 Rep Power: 11 Greeting All!!! @bruno ....thanks for your reply....and I will check that issue... @Alex... thanks for your valuable suggestion... 1. for bc in heating element surface I have used uniformFixedValue 2. for outer wall I have used Code: ``` type externalWallHeatFluxTemperature; kappa solidThermo; Ta uniform 303; h uniform 10; kappaName none; value uniform 300;``` ...the same thing I have used for my previous case also... can you kindly explain what kind of problem you faced with externalWallHeatFluxTemperature bc? I have to check other things as you told and let you know wheather any other issue is there or not... Regards, Baran

 August 24, 2015, 08:54 #6 Senior Member   Alex Join Date: Oct 2013 Posts: 337 Rep Power: 21 Hi baran, You can check youself the problem I faced here. What OF version are you using? If you use 2.3.x or 2.4.x you can fix it by downloading the fixes via github and recompile it. The fix consists of a relaxation factor implemented for the Qr field so that you only need to specify a couple of fields more in the BC specification. By the way, in the BC specification you attached you din't have Qr defined and you need to define it in order to take radiation into account in the boundaries... Hope it helps! Alex wyldckat likes this. __________________ Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!

 August 26, 2015, 07:21 #7 Member   baran Join Date: Aug 2014 Posts: 45 Rep Power: 11 Dear Alex, my OF version is 2.4.x This same case I have run in fluent to compare the two result . As thermal conductivity is very low of this solid zone. Wheather I add radiation at the outer wall does not have any effect. Thermal conductivity of bricks is 0.15 . I want to ask another question..that..if I am applying viewfactor model but wall bc is like convection case then viewfactor effect is come into consideration? Regards, baran

August 31, 2015, 06:02
#8
Member

baran
Join Date: Aug 2014
Posts: 45
Rep Power: 11
Greeting all!!!

This is mesh quality of my geometry...I hope this is not made any problem...

Code:
```Create polyMesh for time = 0

Enabling all (cell, face, edge, point) topology checks.

Enabling all geometry checks.

Time = 0

Mesh stats
points:           1116300
faces:            3270406
internal faces:   3191462
cells:            1076978
faces per cell:   6
boundary patches: 10
point zones:      0
face zones:       13
cell zones:       4

Overall number of cells of each type:
hexahedra:     1076978
prisms:        0
wedges:        0
pyramids:      0
tet wedges:    0
tetrahedra:    0
polyhedra:     0

Checking topology...
Boundary definition OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Topological cell zip-up check OK.
Face-face connectivity OK.
Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
Patch               Faces    Points   Surface topology                   Bounding box
he_surface          13720    13736    ok (closed singly connected)       (0.247 0.251 0.272) (0.917 0.941 1.202)
w_right_side_ref    5952     6111     ok (non-closed singly connected)   (2.6999174e-24 0.15 0.212) (5.2351103e-16 1.036 1.352)
w_left_side_ref     5952     6111     ok (non-closed singly connected)   (1.164 0.15 0.212) (1.164 1.036 1.352)
w_back_ref          12288    12513    ok (non-closed singly connected)   (0 0.15 1.352) (1.164 1.036 1.502)
w_brick_bot         3256     3500     ok (non-closed singly connected)   (0.217 -9.5154073e-16 0.212) (0.947 9.5707519e-16 1.352)
w_bot_ref           7104     7499     ok (non-closed singly connected)   (0 -1.1571817e-15 0.212) (1.164 0.15 1.502)
w_door1             2588     2676     ok (non-closed singly connected)   (0.332 0.356 -0.1) (0.832 0.85600003 -0.05)
w_door2             696      870      ok (non-closed singly connected)   (0.332 0.356 -0.05) (0.832 0.85600003 0)
w_bricks            17028    17343    ok (non-closed singly connected)   (0 -1.1571817e-15 0) (1.164 1.186 0.212)
w_top_ref           10360    10553    ok (non-closed singly connected)   (0 1.036 0.212) (1.164 1.186 1.502)

Checking geometry...
Overall domain bounding box (0 -1.1571817e-15 -0.1) (1.164 1.186 1.502)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (3.2928793e-15 2.2620737e-15 7.0567305e-15) OK.
Max cell openness = 3.3154974e-16 OK.
Max aspect ratio = 13.162501 OK.
Minimum face area = 6.5776377e-06. Maximum face area = 0.00064648215.  Face area magnitudes OK.
Min volume = 8.3282847e-08. Max volume = 7.9145335e-06.  Total volume = 2.0928022.  Cell volumes OK.
Mesh non-orthogonality Max: 69.14912 average: 8.4597446
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.66268921 OK.
Coupled point location match (average 0) OK.
Face tets OK.
Min/max edge length = 0.0016666666 0.032313618 OK.
All angles in faces OK.
Face flatness (1 = flat, 0 = butterfly) : min = 0.99388226  average = 0.99999605
All face flatness OK.
Cell determinant (wellposedness) : minimum: 0.028461416 average: 4.6877314
Cell determinant check OK.
Concave cell check OK.
Face interpolation weight : minimum: 0.10005566 average: 0.49007212
Face interpolation weight check OK.
Face volume ratio : minimum: 0.11131699 average: 0.9662018
Face volume ratio check OK.

Mesh OK.```
Using the convection bc I have get my solution right though using radiation bc case is diverging as I told in my first place..Apart from this temperature variation with time is coming random with radiation bc....I have attached two point is air for this two case.. in picture(in total four...)

Can you suggest what might be the reason??

From the discussion of our previous case it is observed that case is diverging for radiation case...in bricks zone(thermal conductivity-0.15 J/kg K)
So I change the thermal conductivity of bricks from 0.15 to 10. Then run the same case with radiation bc....
Then case is diverging in other zone..fibrothal(thermal conductivity is around 0.15 J/kg K)...So is there is any problem with this radiation bc or radiation to handle high T with small thermal conductivity of insulation..

Please suggest something...mostly this problem is not involve with any mesh issue...??? I have attached the log file for the later case below...

Code:
```Region: fluid Courant Number mean: 0.0198761 max: 0.29878319
Region: fibrothal_in Diffusion Number mean: 5.3692836e-08 max: 3.868369e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.83673

Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8428474e-05, Final residual = 2.3160953e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 5.9872307e-05, Final residual = 2.1848024e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.1347697e-05, Final residual = 1.7257565e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3754107e-05, Final residual = 1.8032295e-09, No Iterations 1
Min/max T:306.56532 939
GAMG:  Solving for p_rgh, Initial residual = 0.004153507, Final residual = 8.7413984e-08, No Iterations 10
GAMG:  Solving for p_rgh, Initial residual = 8.9189776e-06, Final residual = 8.0399224e-08, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 2.1315608e-06, Final residual = 7.7674832e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 6.4079763e-11, global = 8.4405831e-13, cumulative = 1.0816831e-07
GAMG:  Solving for p_rgh, Initial residual = 7.9826171e-07, Final residual = 3.8468735e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 2.8369056e-07, Final residual = 4.4607049e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.209402e-07, Final residual = 2.6745305e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.2064599e-11, global = 8.3155456e-15, cumulative = 1.0816832e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8433956e-06, Final residual = 5.6555918e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 5.846885e-12, Final residual = 5.846885e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 823.55181

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3780627e-06, Final residual = 1.8628724e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9739328e-10, Final residual = 1.9739328e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.0248

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120483e-06, Final residual = 3.4748384e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5734963e-12, Final residual = 3.5734963e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42316
ExecutionTime = 48515.92 s  ClockTime = 49698 s

Region: fluid Courant Number mean: 0.019876 max: 0.29877615
Region: fibrothal_in Diffusion Number mean: 5.3692908e-08 max: 3.8683897e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.83787

Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8490734e-05, Final residual = 2.314818e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 5.9735226e-05, Final residual = 2.1923582e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.1540717e-05, Final residual = 1.7182041e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3757046e-05, Final residual = 1.804325e-09, No Iterations 1

LU Back substitute C matrix..
Min/max T:306.56544 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041498473, Final residual = 9.054912e-08, No Iterations 9
GAMG:  Solving for p_rgh, Initial residual = 8.3165628e-06, Final residual = 7.0594986e-08, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 2.032543e-06, Final residual = 6.9336629e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 5.7201248e-11, global = -9.3147623e-13, cumulative = 1.0816739e-07
GAMG:  Solving for p_rgh, Initial residual = 7.6577489e-07, Final residual = 9.7339006e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 2.8026848e-07, Final residual = 5.1413822e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.298081e-07, Final residual = 2.9943948e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.4703296e-11, global = -6.8827074e-13, cumulative = 1.081667e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8426671e-06, Final residual = 5.6623743e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 4.4247984e-11, Final residual = 4.4247984e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 168.02419 max(T) [0 0 0 1 0 0 0] 823.54449

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3882983e-06, Final residual = 1.8640842e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.0063655e-10, Final residual = 3.0063655e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.07683

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120344e-06, Final residual = 3.4748206e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5760929e-12, Final residual = 3.5760929e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42353
ExecutionTime = 48516.76 s  ClockTime = 49698 s

Region: fluid Courant Number mean: 0.019875904 max: 0.29876907
Region: fibrothal_in Diffusion Number mean: 5.369298e-08 max: 3.8684106e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.83901

Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8363917e-05, Final residual = 2.3111003e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 5.9808245e-05, Final residual = 2.181205e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.1303226e-05, Final residual = 1.7190079e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3769818e-05, Final residual = 1.8025345e-09, No Iterations 1
Min/max T:-34.638404 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041635193, Final residual = 8.7220279e-08, No Iterations 18
GAMG:  Solving for p_rgh, Initial residual = 3.0025266e-05, Final residual = 8.3696645e-08, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 6.9780425e-06, Final residual = 9.4629866e-08, No Iterations 3
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 7.8066502e-11, global = -1.0715968e-11, cumulative = 1.0815598e-07
GAMG:  Solving for p_rgh, Initial residual = 2.6392854e-06, Final residual = 8.7769725e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 9.0381004e-07, Final residual = 4.9359257e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 3.9857535e-07, Final residual = 5.3627197e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 4.4241536e-11, global = 2.0258428e-12, cumulative = 1.0815801e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8427064e-06, Final residual = 5.6629409e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9117983e-11, Final residual = 1.9117983e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] -34.64088 max(T) [0 0 0 1 0 0 0] 823.55061

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3881957e-06, Final residual = 1.8640995e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9768437e-10, Final residual = 1.9768437e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.07814

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120205e-06, Final residual = 3.4748029e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5713957e-12, Final residual = 3.5713957e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42391
ExecutionTime = 48517.36 s  ClockTime = 49699 s

Region: fluid Courant Number mean: 0.019875807 max: 0.29875958
Region: fibrothal_in Diffusion Number mean: 5.3693051e-08 max: 3.8684315e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.84016

Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 8.1108496e-05, Final residual = 2.5818077e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 6.134127e-05, Final residual = 2.4355749e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.5046122e-05, Final residual = 1.9803553e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3767232e-05, Final residual = 1.8025597e-09, No Iterations 1
Min/max T:168.04889 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041488398, Final residual = 9.7922006e-08, No Iterations 16
GAMG:  Solving for p_rgh, Initial residual = 2.5548778e-05, Final residual = 8.2376033e-08, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 6.7243635e-06, Final residual = 5.251697e-08, No Iterations 4
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 4.3325191e-11, global = 5.3072732e-12, cumulative = 1.0816332e-07
GAMG:  Solving for p_rgh, Initial residual = 1.8993958e-06, Final residual = 6.9772195e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 6.1908036e-07, Final residual = 8.0077444e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 2.4772369e-07, Final residual = 4.5438216e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 3.7486014e-11, global = 1.2021921e-12, cumulative = 1.0816452e-07

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120066e-06, Final residual = 3.4747852e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5740577e-12, Final residual = 3.5740577e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42429
ExecutionTime = 48517.93 s  ClockTime = 49700 s

Region: fluid Courant Number mean: 0.019875723 max: 0.29875153
Region: fibrothal_in Diffusion Number mean: 5.3693123e-08 max: 3.8684525e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.8413

Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8970139e-05, Final residual = 2.3571827e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 6.0058436e-05, Final residual = 2.2336877e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.2795778e-05, Final residual = 1.7421106e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3770425e-05, Final residual = 1.8043668e-09, No Iterations 1
Min/max T:-35.535871 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041525003, Final residual = 8.3978618e-08, No Iterations 16
GAMG:  Solving for p_rgh, Initial residual = 2.0716891e-05, Final residual = 8.414588e-08, No Iterations 6
GAMG:  Solving for p_rgh, Initial residual = 5.9691193e-06, Final residual = 6.361722e-08, No Iterations 4
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 5.2482977e-11, global = -1.8655448e-12, cumulative = 1.0816265e-07
GAMG:  Solving for p_rgh, Initial residual = 1.6250719e-06, Final residual = 7.813847e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 4.7865432e-07, Final residual = 6.8283963e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.8631846e-07, Final residual = 3.5284387e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.9109187e-11, global = -2.3103795e-13, cumulative = 1.0816242e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8424178e-06, Final residual = 5.6627448e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 7.5644313e-12, Final residual = 7.5644313e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] -35.538367 max(T) [0 0 0 1 0 0 0] 823.55579

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3879905e-06, Final residual = 1.864035e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9767345e-10, Final residual = 1.9767345e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.08076

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1119927e-06, Final residual = 3.4747675e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5731187e-12, Final residual = 3.5731187e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42467
ExecutionTime = 48518.51 s  ClockTime = 49700 s

Region: fluid Courant Number mean: 0.019875633 max: 0.29874413
Region: fibrothal_in Diffusion Number mean: 5.3693195e-08 max: 3.8684734e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394```
Regards,
Baran
Attached Images
 compare.JPG (42.1 KB, 50 views)

 September 1, 2015, 18:37 #9 Senior Member   Alex Join Date: Oct 2013 Posts: 337 Rep Power: 21 Ok baran, I guess that you are still using externalWallHeatFluxTemperature BC... If so, update your source code with the latest patches and corrections (in case you haven't done it for the last 3 months or so... If you installed OF 2.4.x less than 3 months ago it shouldn't be necessary...). Once you have uploaded it and recompiled it try using a similar specification for external boundaries to this one: Code: ``` myPatch { type externalWallHeatFluxTemperature; kappa fluidThermo; q uniform 1000; Ta uniform 300.0; h uniform 10.0; thicknessLayers (0.1 0.2 0.3 0.4); kappaLayers (1 2 3 4); value uniform 300.0; kappaName none; Qr Qr; relaxation 1; // try with lower values, using 1 will make no difference. Maybe 0.1 would do the trick... }``` This piece of code I have taken it from here. Hope it helps. Best regards, Alex wht likes this. __________________ Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!

 September 4, 2015, 07:31 #10 Member   baran Join Date: Aug 2014 Posts: 45 Rep Power: 11 Dear Alex, I have changed the outer wall bc of externalWallHeatFluxTemperature as it is already available in of2.4 ... Code: ``` { type externalWallHeatFluxTemperature; kappa solidThermo; //q uniform 1000; Ta uniform 300.0; h uniform 10.0; //thicknessLayers (0.1 0.2 0.3 0.4); //kappaLayers (1 2 3 4); value uniform 300.0; kappaName none; Qr Qr; relaxation 1; }``` Still I get the same problem.......and it is started diverging due to some low temperature in solid_bricks which have constant property of k= 0.15 j/kg K and other value also.... fvSolution... Code: ```solvers { h { solver PCG; preconditioner DIC; tolerance 1e-06; relTol 0.1; } hFinal { \$h; tolerance 1e-06; relTol 0; } } PIMPLE { nNonOrthogonalCorrectors 2; }``` fvScheme... Code: ```ddtSchemes { default Euler; } gradSchemes { default Gauss linear; } divSchemes { default none; } laplacianSchemes { default none; laplacian(alpha,h) Gauss linear limited 0.333; } interpolationSchemes { default linear; } snGradSchemes { default limited 0.333; } fluxRequired { default no; }``` this is log file of diverging section... Code: ```Region: fluid Courant Number mean: 0.011803868 max: 0.29978066 Region: fibrothal_in Diffusion Number mean: 5.984852e-08 max: 3.6395751e-07 Region: solid_bricks Diffusion Number mean: 4.325115e-08 max: 2.3223831e-07 Region: unifrax_out Diffusion Number mean: 1.2271976e-07 max: 3.7808866e-07 deltaT = 0.00134182 Time = 61.349217 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.00020252946, Final residual = 1.0480067e-08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00022700634, Final residual = 4.9277215e-09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.00021673457, Final residual = 8.2935081e-09, No Iterations 2 DILUPBiCG: Solving for h, Initial residual = 7.0113698e-05, Final residual = 5.4885426e-10, No Iterations 2 Min/max T:314.12367 753 GAMG: Solving for p_rgh, Initial residual = 0.0011703758, Final residual = 8.8669323e-08, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 4.657791e-06, Final residual = 5.7582968e-08, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 1.1551078e-06, Final residual = 4.3470744e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 3.9981212e-10, global = -2.0513208e-11, cumulative = -1.7388678e-08 GAMG: Solving for p_rgh, Initial residual = 1.3509646e-06, Final residual = 7.2930855e-08, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 2.5230028e-07, Final residual = 5.9736719e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 1.1260898e-07, Final residual = 4.3606164e-08, No Iterations 1 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 4.0105979e-10, global = -3.4002934e-11, cumulative = -1.7422681e-08 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 1.3847821e-05, Final residual = 1.3047331e-11, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.3725991e-11, Final residual = 1.3725991e-11, No Iterations 0 DICPCG: Solving for h, Initial residual = 1.3725991e-11, Final residual = 1.3725991e-11, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 611.48428 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 1.0430615e-05, Final residual = 6.5189609e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 9.8068229e-12, Final residual = 9.8068229e-12, No Iterations 0 DICPCG: Solving for h, Initial residual = 9.8068229e-12, Final residual = 9.8068229e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 666.81513 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 2.4035529e-05, Final residual = 1.605035e-11, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.544039e-09, Final residual = 1.544039e-09, No Iterations 0 DICPCG: Solving for h, Initial residual = 1.544039e-09, Final residual = 1.544039e-09, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 300.03595 ExecutionTime = 16126.77 s ClockTime = 16559 s Region: fluid Courant Number mean: 0.011803874 max: 0.29977296 Region: fibrothal_in Diffusion Number mean: 5.9848554e-08 max: 3.6395834e-07 Region: solid_bricks Diffusion Number mean: 4.325115e-08 max: 2.3223831e-07 Region: unifrax_out Diffusion Number mean: 1.2271976e-07 max: 3.7808866e-07 deltaT = 0.00134182 Time = 61.350559 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.0002025609, Final residual = 1.1910169e-08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00022700465, Final residual = 4.884998e-09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.00021670343, Final residual = 8.4535848e-09, No Iterations 2 DILUPBiCG: Solving for h, Initial residual = 7.0106796e-05, Final residual = 5.5296829e-10, No Iterations 2 LU Back substitute C matrix.. Min/max T:314.12101 753 GAMG: Solving for p_rgh, Initial residual = 0.0011700388, Final residual = 7.9481395e-08, No Iterations 6 GAMG: Solving for p_rgh, Initial residual = 4.6523857e-06, Final residual = 5.1471481e-08, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 1.1486924e-06, Final residual = 4.0637e-08, No Iterations 2 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 3.7375369e-10, global = -4.3799329e-12, cumulative = -1.7427061e-08 GAMG: Solving for p_rgh, Initial residual = 1.3509856e-06, Final residual = 6.9778436e-08, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 2.5777917e-07, Final residual = 5.2959357e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 1.065836e-07, Final residual = 3.6159249e-08, No Iterations 1 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 3.3257513e-10, global = -3.1279595e-11, cumulative = -1.745834e-08 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 1.3848359e-05, Final residual = 1.3046006e-11, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.5699743e-11, Final residual = 1.5699743e-11, No Iterations 0 DICPCG: Solving for h, Initial residual = 1.5699743e-11, Final residual = 1.5699743e-11, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 611.4786 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 1.0418483e-05, Final residual = 6.5202524e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 2.4807543e-09, Final residual = 2.4807543e-09, No Iterations 0 DICPCG: Solving for h, Initial residual = 2.4807543e-09, Final residual = 2.4807543e-09, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 289.72511 max(T) [0 0 0 1 0 0 0] 649.88563 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 2.4034686e-05, Final residual = 1.6049802e-11, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.6219618e-09, Final residual = 1.6219618e-09, No Iterations 0 DICPCG: Solving for h, Initial residual = 1.6219618e-09, Final residual = 1.6219618e-09, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 300.03596 ExecutionTime = 16127.5 s ClockTime = 16560 s Region: fluid Courant Number mean: 0.011803878 max: 0.29976523 Region: fibrothal_in Diffusion Number mean: 5.9848588e-08 max: 3.6395917e-07 Region: solid_bricks Diffusion Number mean: 4.325115e-08 max: 2.3223831e-07 Region: unifrax_out Diffusion Number mean: 1.2271976e-07 max: 3.7808866e-07 deltaT = 0.00134182 Time = 61.351901 Solving for fluid region fluid diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Ux, Initial residual = 0.000202575, Final residual = 1.1953834e-08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00022699901, Final residual = 4.9589681e-09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.00021670665, Final residual = 8.6043666e-09, No Iterations 2 DILUPBiCG: Solving for h, Initial residual = 7.0163301e-05, Final residual = 5.5663264e-10, No Iterations 2 Min/max T:289.72512 753 GAMG: Solving for p_rgh, Initial residual = 0.0011745932, Final residual = 9.461503e-08, No Iterations 23 GAMG: Solving for p_rgh, Initial residual = 1.3703751e-05, Final residual = 9.2266387e-08, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 3.2030153e-06, Final residual = 7.2234752e-08, No Iterations 3 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 6.6436148e-10, global = -1.1345981e-10, cumulative = -1.75718e-08 GAMG: Solving for p_rgh, Initial residual = 2.1936572e-06, Final residual = 7.8329574e-08, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 5.4352731e-07, Final residual = 9.250977e-08, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 2.3308027e-07, Final residual = 5.8853582e-08, No Iterations 1 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 time step continuity errors (fluid): sum local = 5.4130436e-10, global = 5.585416e-11, cumulative = -1.7515946e-08 Solving for solid region fibrothal_in DICPCG: Solving for h, Initial residual = 1.3847885e-05, Final residual = 1.3045515e-11, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.3991418e-11, Final residual = 1.3991418e-11, No Iterations 0 DICPCG: Solving for h, Initial residual = 1.3991418e-11, Final residual = 1.3991418e-11, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 611.48274 Solving for solid region solid_bricks DICPCG: Solving for h, Initial residual = 1.0418394e-05, Final residual = 6.519972e-12, No Iterations 1 DICPCG: Solving for h, Initial residual = 9.8457579e-12, Final residual = 9.8457579e-12, No Iterations 0 DICPCG: Solving for h, Initial residual = 9.8457579e-12, Final residual = 9.8457579e-12, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 289.71756 max(T) [0 0 0 1 0 0 0] 649.89343 Solving for solid region unifrax_out DICPCG: Solving for h, Initial residual = 2.4034443e-05, Final residual = 1.6049873e-11, No Iterations 1 DICPCG: Solving for h, Initial residual = 1.6956056e-09, Final residual = 1.6956056e-09, No Iterations 0 DICPCG: Solving for h, Initial residual = 1.6956056e-09, Final residual = 1.6956056e-09, No Iterations 0 Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 300.03596 ExecutionTime = 16127.98 s ClockTime = 16561 s``` I can't understand why suddenly there is low temperature in solid_bricks....please suggest something... Regards, Baran

 December 17, 2019, 17:36 #11 New Member   Dániel Bakonyi Join Date: Dec 2019 Location: Budapest, Hungary Posts: 2 Rep Power: 0 Dear all, I am currenlty facing what seems to be the same problem. I am using OF 7 and chtMultiRegionFoam and I am trying to simulate the inside of a furnace where a bunch of solid pans are stacked on each other. My setup is steadyState and it runs just fine without radiation. My settings are based mostly on the OF6 MultiRegionHeaterRadiation tutorial. However, as soon as I introduce radiation to the model it crashes in a few iterations with the a negative initial temperature error, or because the max number of iterations is exceeded by the h solver (if I try to constarin T with limitTemperature in the solid). fluid region thermal and radiation properties: Code: ```thermoType { type heRhoThermo; mixture pureMixture; transport polynomial; thermo hPolynomial; equationOfState icoPolynomial; specie specie; energy sensibleEnthalpy; } ... radiation on; riadaitionModel P1; solverFreq 1; absorptionEmissionModel constant; constantCoeffs { absorptivity 0.07; emissivity 0.037; E 0; } scatterModel none; sootModel none;``` and for the solid regions: Code: ```thermoType { type heSolidThermo; mixture pureMixture; transport constIso; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } mixture { specie { molWeight 28; } equationOfState { rho 1380; } transport { kappa 1; } thermodynamics { Hf 0; Cp 900; } } ... radiation on; radiationModel opaqueSolid; absorptionEmissionModel constant; constantCoeffs { absorptivity 0; emissivity 0.9; E 0; }``` the numerical settings I am using for the fluid region: Code: ```ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss upwind; div(phi,h) bounded Gauss upwind; div(phi,epsilon) bounded Gauss upwind; div(phi,k) bounded Gauss upwind; div(phi,K) bounded Gauss linear; div(phiv,p) Gauss upwind; div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear uncorrected; } interpolationSchemes { default linear; } snGradSchemes { default uncorrected; } ... solvers { ... "G.*" { solver PCG; preconditioner DIC; tolerance 1e-5; relTol 0.1; } ... } relaxationFactors { fields { "rho.*" 1.0; "p_rgh.*" 0.7; } equations { "U.*" 0.3; "h.*" 0.7; "k.*" 0.7; "epsilon.*" 0.7; "G" 0.7; } }``` And for the solid regions: Code: ```ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; } laplacianSchemes { default none; laplacian(alpha,h) Gauss linear uncorrected; } interpolationSchemes { default linear; } snGradSchemes { default uncorrected; }``` The radiation related boundary conditions for the fluid: Code: ```//T BC for the extrenal walls of the furnace { type externalWallHeatFluxTemperature; mode coefficient; h uniform 8; Ta constant 1000; value \$internalField; kappaLayers (0.5); thicknessLayers (0.25); kappaMethod fluidThermo; qr qr; } //T BC for the faces of the solid regions in the middle of the fluid { type compressible::turbulentTemperatureRadCoupledMixed; Tnbr T; kappaMethod fluidThermo; qrNbr none; qr qr; value \$internalField; } //G for the external walls { type MarshakRadiation; emissivityMode lookup; emissivity uniform 0.9; value \$internalField; } //G for the internal walls { type MarshakRadiation; emissivityMode solidRadiation; emissivity uniform 0.9; value \$internalField; }``` And for the solid: Code: ```{ type compressible::turbulentTemperatureRadCoupledMixed; Tnbr T; kappaMethod solidThermo; qrNbr qr; qr none; value \$internalField; }``` I checked the results with ParaView as suggested earlier in this thred. Everything is fine before the radiation is added and then the problem is with the solid region not with the extrenal walls. When I plot the temperature for the surface_to_fluid patches they start to diverge in the negative direction from the temperature in the fluid_to_solid patches at the same place. the r field plotted on the same surafces is negative where this happens. https://app.box.com/s/bhz1wlgcgt3iobxfnnuu35z5poibi0hk https://app.box.com/s/rqgmuf541vw8ta88fnqftcipjquwfxdg and finally the temprature gets negative in the edges of the solid region before everything goes to hell: https://app.box.com/s/8mwikreoznywcdtnnayjrh3175lttehs The solid regions is loosing thermal energy and I dont know why. I have read several of zfaraday's posts about radiation modeling but there is no relaxation option for the turbuelntTemepratureRadCoupledMixed bc that I can find. Is there something obviously wrong in my setup? I am completely stuck, so any help would be greatly appreciated! Dear Baran, I know it has been quite a while, but have you found asolution for your problem? Last edited by Daniel Bakonyi; December 18, 2019 at 07:30.