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June 8, 2010, 09:21 |
lift and drag on ship superstructures
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#1 |
Senior Member
Join Date: Feb 2010
Posts: 213
Rep Power: 17 |
I'm going to study the aerodynamic aspect of ship superstructures. I started with a simple 2D model (see pic 1-2), a top view of a superstructure (abot 30x80 m). I used the simpleFoam solver (with wall functions) and I'd like to have some suggestions. I already studied airfoils and propeller blades in water (convergence before 1000 iterations and correct y+), but now I think I have a few problems about convergence and y+. Here are my boundary conditions:
p Code:
#include "initialConditions" dimensions [0 2 -2 0 0 0 0]; internalField uniform $pressure; boundaryField { inlet { type zeroGradient; } #include "frontBackPatches" outlet { type fixedValue; value $internalField; } main_body { type kqRWallFunction; value $internalField; } } Code:
#include "initialConditions" dimensions [0 1 -1 0 0 0 0]; internalField uniform $flowVelocity; boundaryField { #include "fixedInlet" #include "frontBackPatches" outlet { type inletOutlet; inletValue uniform (0 0 0); value $internalField; } main_body { type fixedValue; value uniform (0 0 0); } } Code:
#include "initialConditions" dimensions [0 2 -2 0 0 0 0]; internalField uniform $turbulentK; boundaryField { #include "fixedInlet" #include "frontBackPatches" main_body { type kqRWallFunction; value $internalField; } outlet { type inletOutlet; inletValue $internalField; value $internalField; } } Code:
#include "initialConditions" dimensions [0 0 -1 0 0 0 0]; internalField uniform $turbulentOmega; boundaryField { #include "fixedInlet" #include "frontBackPatches" main_body { type kqRWallFunction; value $internalField; } outlet { type inletOutlet; inletValue $internalField; value $internalField; } } Code:
FoamFile { version 2.0; format ascii; class dictionary; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; // grad(U) cellLimited Gauss linear 1; } divSchemes { default none; div(phi,U) Gauss linearUpwindV Gauss linear; div(phi,k) Gauss upwind; div(phi,omega) Gauss upwind; div((nuEff*dev(grad(U).T()))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; // default Gauss linear limited 0.5; // default Gauss linear limited 0.333; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; } Code:
FoamFile { version 2.0; format ascii; class dictionary; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { p { solver GAMG; tolerance 1e-7; relTol 0.1; smoother GaussSeidel; nPreSweeps 0; nPostSweeps 2; cacheAgglomeration on; agglomerator faceAreaPair; nCellsInCoarsestLevel 10; mergeLevels 1; }; U { solver smoothSolver; smoother GaussSeidel; tolerance 1e-8; relTol 0.1; nSweeps 1; }; k { solver smoothSolver; smoother GaussSeidel; tolerance 1e-8; relTol 0.1; nSweeps 1; }; omega { solver smoothSolver; smoother GaussSeidel; tolerance 1e-8; relTol 0.1; nSweeps 1; }; } SIMPLE { nNonOrthogonalCorrectors 0; convergenceCriterion 1e-5; } relaxationFactors { p 0.3; U 0.7; k 0.7; omega 0.7; } I thought about a different mesh (see pic3) but I'm in troubles with inlet and outlet boundary conditions for p and U. I'd like to set different apparent winds, so I believe I can't establish which patch is an inlet or outlet one beforehand. Are there any derived boundary conditions, similar to inletOutlet and outletInlet, to that aim? Thanks for your help. |
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June 8, 2010, 09:22 |
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#2 |
Senior Member
Join Date: Feb 2010
Posts: 213
Rep Power: 17 |
Here is pic2
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June 8, 2010, 09:23 |
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#3 |
Senior Member
Join Date: Feb 2010
Posts: 213
Rep Power: 17 |
Here is pic3
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June 8, 2010, 12:30 |
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#4 |
Senior Member
Join Date: Feb 2010
Posts: 213
Rep Power: 17 |
I changed the outlet bc in the U file:
Code:
outlet { type inletOutlet; inletValue uniform (0 0 0); value uniform (0 0 0); } Code:
Time = 1990 smoothSolver: Solving for Ux, Initial residual = 0.0194878, Final residual = 0.00140397, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00675477, Final residual = 0.000472691, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0338792, Final residual = 0.00292316, No Iterations 2 time step continuity errors : sum local = 6.87276e-06, global = 4.32326e-07, cumulative = 0.000196135 smoothSolver: Solving for omega, Initial residual = 0.000500113, Final residual = 4.49831e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00747582, Final residual = 0.000625669, No Iterations 3 ExecutionTime = 737.82 s ClockTime = 889 s forces output: forces(pressure, viscous)((1373.57 6530.95 1.82693e-15) (14.9359 2.98526 -5.12444e-18)) moment(pressure, viscous)((-3265.47 686.785 231467) (-1.49263 7.46796 93.4669)) forceCoeffs output: Cd = 1.10008 Cl = 0.714475 Cm = 0 Time = 1991 smoothSolver: Solving for Ux, Initial residual = 0.0191039, Final residual = 0.001403, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00664963, Final residual = 0.000467334, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0339034, Final residual = 0.00296081, No Iterations 2 time step continuity errors : sum local = 6.91286e-06, global = 5.84111e-07, cumulative = 0.000196719 smoothSolver: Solving for omega, Initial residual = 0.000495335, Final residual = 4.50325e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00712408, Final residual = 0.000611907, No Iterations 3 ExecutionTime = 738.23 s ClockTime = 889 s forces output: forces(pressure, viscous)((1270.77 6686.6 1.88893e-15) (14.8198 3.08212 -4.86763e-18)) moment(pressure, viscous)((-3343.3 635.386 237418) (-1.54106 7.40989 98.9058)) forceCoeffs output: Cd = 1.10742 Cl = 0.750391 Cm = 0 Time = 1992 smoothSolver: Solving for Ux, Initial residual = 0.0186364, Final residual = 0.00139815, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00654604, Final residual = 0.000462334, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0342788, Final residual = 0.00299029, No Iterations 2 time step continuity errors : sum local = 6.93894e-06, global = 6.87427e-07, cumulative = 0.000197406 smoothSolver: Solving for omega, Initial residual = 0.000490721, Final residual = 4.50313e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00676195, Final residual = 0.000597454, No Iterations 3 ExecutionTime = 738.63 s ClockTime = 889 s forces output: forces(pressure, viscous)((1167.46 6845.19 1.95158e-15) (14.7014 3.17815 -4.62007e-18)) moment(pressure, viscous)((-3422.6 583.732 243468) (-1.58908 7.35069 104.192)) forceCoeffs output: Cd = 1.11509 Cl = 0.786788 Cm = 0 Time = 1993 smoothSolver: Solving for Ux, Initial residual = 0.0181001, Final residual = 0.00138872, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00644689, Final residual = 0.000457899, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0347106, Final residual = 0.00300199, No Iterations 2 time step continuity errors : sum local = 6.93254e-06, global = 7.49189e-07, cumulative = 0.000198155 smoothSolver: Solving for omega, Initial residual = 0.000486142, Final residual = 4.50867e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.0064024, Final residual = 0.000582749, No Iterations 3 ExecutionTime = 738.98 s ClockTime = 890 s forces output: forces(pressure, viscous)((1062.53 7008.45 2.01487e-15) (14.5802 3.2732 -4.46006e-18)) moment(pressure, viscous)((-3504.23 531.263 249696) (-1.6366 7.29011 109.348)) forceCoeffs output: Cd = 1.12318 Cl = 0.824058 Cm = 0 Time = 1994 smoothSolver: Solving for Ux, Initial residual = 0.0175231, Final residual = 0.00137507, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00635044, Final residual = 0.000453938, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0347473, Final residual = 0.00297488, No Iterations 2 time step continuity errors : sum local = 6.85089e-06, global = 7.57133e-07, cumulative = 0.000198913 smoothSolver: Solving for omega, Initial residual = 0.000481471, Final residual = 4.5085e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00605224, Final residual = 0.000567726, No Iterations 3 ExecutionTime = 739.26 s ClockTime = 890 s forces output: forces(pressure, viscous)((955.289 7176.48 2.07895e-15) (14.4579 3.36829 -4.57355e-18)) moment(pressure, viscous)((-3588.24 477.645 256113) (-1.68415 7.22897 114.367)) forceCoeffs output: Cd = 1.13162 Cl = 0.86231 Cm = 0 Time = 1995 smoothSolver: Solving for Ux, Initial residual = 0.016937, Final residual = 0.00135761, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00625675, Final residual = 0.000450832, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0342087, Final residual = 0.0029106, No Iterations 2 time step continuity errors : sum local = 6.70063e-06, global = 7.01239e-07, cumulative = 0.000199614 smoothSolver: Solving for omega, Initial residual = 0.000477093, Final residual = 4.51017e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00571846, Final residual = 0.000553258, No Iterations 3 ExecutionTime = 739.57 s ClockTime = 891 s forces output: forces(pressure, viscous)((846.582 7347.19 2.14345e-15) (14.3335 3.46361 -4.82403e-18)) moment(pressure, viscous)((-3673.59 423.291 262636) (-1.73181 7.16675 119.279)) forceCoeffs output: Cd = 1.14023 Cl = 0.90114 Cm = 0 Time = 1996 smoothSolver: Solving for Ux, Initial residual = 0.0163787, Final residual = 0.00133729, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00615668, Final residual = 0.000448527, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0330994, Final residual = 0.00282895, No Iterations 2 time step continuity errors : sum local = 6.52723e-06, global = 5.932e-07, cumulative = 0.000200207 smoothSolver: Solving for omega, Initial residual = 0.000472781, Final residual = 4.51361e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00540995, Final residual = 0.000539806, No Iterations 3 ExecutionTime = 739.9 s ClockTime = 891 s forces output: forces(pressure, viscous)((737.789 7516.79 2.20766e-15) (14.2067 3.55839 -5.0285e-18)) moment(pressure, viscous)((-3758.39 368.895 269100) (-1.7792 7.10333 124.06)) forceCoeffs output: Cd = 1.14867 Cl = 0.939827 Cm = 0 Time = 1997 smoothSolver: Solving for Ux, Initial residual = 0.0158759, Final residual = 0.00131455, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00605029, Final residual = 0.000446912, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0316095, Final residual = 0.00272361, No Iterations 2 time step continuity errors : sum local = 6.31621e-06, global = 4.49215e-07, cumulative = 0.000200656 smoothSolver: Solving for omega, Initial residual = 0.00046907, Final residual = 4.51689e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00512825, Final residual = 0.000303408, No Iterations 4 ExecutionTime = 740.26 s ClockTime = 891 s forces output: forces(pressure, viscous)((628.927 7684.96 2.27177e-15) (14.0771 3.65174 -5.07449e-18)) moment(pressure, viscous)((-3842.48 314.464 275471) (-1.82587 7.03855 128.654)) forceCoeffs output: Cd = 1.1569 Cl = 0.978326 Cm = 0 Time = 1998 smoothSolver: Solving for Ux, Initial residual = 0.0154559, Final residual = 0.00129072, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00593228, Final residual = 0.000445859, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0298766, Final residual = 0.00256894, No Iterations 2 time step continuity errors : sum local = 6.00456e-06, global = 3.05541e-07, cumulative = 0.000200962 smoothSolver: Solving for omega, Initial residual = 0.000465651, Final residual = 4.52165e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00486797, Final residual = 0.000301362, No Iterations 4 ExecutionTime = 740.64 s ClockTime = 892 s forces output: forces(pressure, viscous)((520.223 7851.81 2.336e-15) (13.9439 3.74411 -5.15829e-18)) moment(pressure, viscous)((-3925.91 260.111 281738) (-1.87205 6.97195 133.108)) forceCoeffs output: Cd = 1.16496 Cl = 1.01662 Cm = 0 Time = 1999 smoothSolver: Solving for Ux, Initial residual = 0.0151284, Final residual = 0.00126767, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00580735, Final residual = 0.000445745, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0279414, Final residual = 0.00237774, No Iterations 2 time step continuity errors : sum local = 5.61149e-06, global = 1.95978e-07, cumulative = 0.000201158 smoothSolver: Solving for omega, Initial residual = 0.000462446, Final residual = 4.52691e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00465002, Final residual = 0.000301046, No Iterations 4 ExecutionTime = 740.99 s ClockTime = 892 s forces output: forces(pressure, viscous)((413.176 8014.36 2.40016e-15) (13.8087 3.83569 -5.36615e-18)) moment(pressure, viscous)((-4007.18 206.588 287786) (-1.91784 6.90434 137.402)) forceCoeffs output: Cd = 1.17267 Cl = 1.05409 Cm = 0 Time = 2000 smoothSolver: Solving for Ux, Initial residual = 0.0148846, Final residual = 0.00124765, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.00568015, Final residual = 0.000446866, No Iterations 4 GAMG: Solving for p, Initial residual = 0.0257257, Final residual = 0.0021881, No Iterations 2 time step continuity errors : sum local = 5.21265e-06, global = 8.4432e-08, cumulative = 0.000201242 smoothSolver: Solving for omega, Initial residual = 0.00045956, Final residual = 4.53259e-05, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.00447416, Final residual = 0.000302495, No Iterations 4 ExecutionTime = 741.69 s ClockTime = 893 s forces output: forces(pressure, viscous)((308.845 8170.8 2.46409e-15) (13.6723 3.9266 -5.67718e-18)) moment(pressure, viscous)((-4085.4 154.422 293552) (-1.9633 6.83616 141.523)) forceCoeffs output: Cd = 1.17989 Cl = 1.09033 Cm = 0 End Finalising parallel run |
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