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Heat transfer simulation with low-Re modelling blowing up

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Old   June 15, 2012, 17:55
Default Heat transfer simulation with low-Re modelling blowing up
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Jubayer
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Hi,

I am simulating atmospheric boundary layer flow over an inclined plate with application to solar panels. I am looking into the heat transfer from the panel. At the domain inlet, I am using mean profiles of velocity, turbulent kinetic energy and specific dissipation rate of turbulence using SST k-omega turbulence model. At the outlet of the domain I am using fixed pressure of 0 Pa. Without low-Re mesh (y+ around 200), for getting pressures on the panel (for wind load estimation), simulations runs fine. However for the heat transfer simulations with y+<1, simulation is blowing up as the courant number gets bigger and bigger (even with time step size of 10^-9 s) although wind speed is low for the heat transfer case (5 m/s at 10m height whereas for the wind loading simulation I have used 25 m/s without no problem). I am using buoyantBoussinesqPimpleFoam solver for the heat transfer simulation. My fvSchemes for heat transfer looks like the following:

ddtSchemes
{
default Euler;
}

gradSchemes
{
default cellLimited leastSquares 1.0;
}

divSchemes
{
default none;
div(phi,U) Gauss vanLeer;
div(phi,T) Gauss vanLeer;
div(phi,k) Gauss vanLeer;
div(phi,omega) Gauss vanLeer ;
div(phi,R) Gauss vanLeer ;
div(R) Gauss limitedLinear 1 ;
div((nuEff*dev(T(grad(U))))) Gauss linear limited 0.5 ;
}

laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear limited 0.5;
laplacian((1|A(U)),p_rgh) Gauss linear limited 0.5 ;
laplacian(kappaEff,T) Gauss linear limited 0.5;
laplacian(DkEff,k) Gauss linear limited 0.5;
laplacian(DomegaEff,omega) Gauss linear limited 0.5;
laplacian(DREff,R) Gauss linear limited 0.5;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default limited 0.5;
}

fluxRequired
{
default no;
p_rgh ;
}

Below is a glimpse when simulation is blowing up

---------------------------------------------------------------------
Time = 0.00010097

Courant Number mean: 4.7345636e-07 max: 1233.7809
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 1.2870124e-06, Final residual = 7.1891992e-09, No Iterations 2
DICPCG: Solving for p_rgh, Initial residual = 0.76361335, Final residual = 0.00097027484, No Iterations 120
time step continuity errors : sum local = 1.4489948e-10, global = 9.5209982e-12, cumulative = -6.5187104e-12
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 2.5226717e-06, Final residual = 8.3556918e-09, No Iterations 101
DICPCG: Solving for p_rgh, Initial residual = 0.69872336, Final residual = 0.00098344698, No Iterations 419
time step continuity errors : sum local = 4.5798547e-10, global = 1.8186047e-11, cumulative = 1.1667336e-11
DILUPBiCG: Solving for omega, Initial residual = 0.00050378054, Final residual = 5.0894516e-09, No Iterations 109
bounding omega, min: -1.6530455e+12 max: 3.8839584e+12 average: 59305422
DILUPBiCG: Solving for k, Initial residual = 0.00035940466, Final residual = 5.3762244e-09, No Iterations 99
bounding k, min: -8.6846115e+11 max: 2.7713031e+12 average: 1585310.7
ExecutionTime = 13894.57 s ClockTime = 13905 s

Time = 0.00010098

Courant Number mean: 6.9096584e-07 max: 2692.3661
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 3.1575455e-06, Final residual = 9.7394175e-09, No Iterations 2
DICPCG: Solving for p_rgh, Initial residual = 0.74447529, Final residual = 0.00097299859, No Iterations 97
time step continuity errors : sum local = 2.4875275e-10, global = 1.7993474e-11, cumulative = 2.9660811e-11
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 3.7889403e-06, Final residual = 5.7741675e-09, No Iterations 153
DICPCG: Solving for p_rgh, Initial residual = 0.7661894, Final residual = 0.00099395397, No Iterations 444
time step continuity errors : sum local = 2.5940091e-09, global = 8.240833e-11, cumulative = 1.1206914e-10
DILUPBiCG: Solving for omega, Initial residual = 0.00087259239, Final residual = 8.3974792e-09, No Iterations 79
bounding omega, min: -7.5412548e+11 max: 1.9226682e+12 average: 94265063
DILUPBiCG: Solving for k, Initial residual = 0.0015909616, Final residual = 8.3691303e-09, No Iterations 68
bounding k, min: -3.2118556e+11 max: 2.0770441e+12 average: 4234488.5
ExecutionTime = 14445.9 s ClockTime = 14456 s

Time = 0.00010099

Courant Number mean: 1.9504303e-06 max: 5747.6202
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 1.6991088e-05, Final residual = 2.6964904e-09, No Iterations 4
DICPCG: Solving for p_rgh, Initial residual = 0.75607356, Final residual = 0.00099111414, No Iterations 201
time step continuity errors : sum local = 8.4048694e-10, global = 3.4520769e-10, cumulative = 4.5727683e-10
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 2.9118025e-05, Final residual = 7.2186118e-09, No Iterations 419
DICPCG: Solving for p_rgh, Initial residual = 0.84296989, Final residual = 0.00095307524, No Iterations 706
time step continuity errors : sum local = 4.7938114e-09, global = 1.1318495e-09, cumulative = 1.5891263e-09
DILUPBiCG: Solving for omega, Initial residual = 0.0067051264, Final residual = 7.1001411e-09, No Iterations 328
bounding omega, min: -1.4353841e+14 max: 1.3961573e+14 average: 1.7683567e+09
DILUPBiCG: Solving for k, Initial residual = 0.0091318156, Final residual = 9.0899654e-09, No Iterations 214
bounding k, min: -6.8698845e+11 max: 1.075334e+13 average: 19477433
ExecutionTime = 15914.84 s ClockTime = 15926 s

Time = 0.000101

Courant Number mean: 9.2903545e-06 max: 33446.887
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 3.5918305e-05, Final residual = 7.4009402e-09, No Iterations 3
DICPCG: Solving for p_rgh, Initial residual = 0.51530912, Final residual = 0.00098150633, No Iterations 87
time step continuity errors : sum local = 5.6978294e-09, global = 1.1952208e-09, cumulative = 2.7843471e-09
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 9.5350344e-05, Final residual = 6.6825388e-07, No Iterations 1001
DICPCG: Solving for p_rgh, Initial residual = 0.64166418, Final residual = 0.026321393, No Iterations 1001
time step continuity errors : sum local = 1.7760159e-06, global = 1.8077374e-09, cumulative = 4.5920845e-09
DILUPBiCG: Solving for omega, Initial residual = 0.02237984, Final residual = 6.0043179e-09, No Iterations 420
bounding omega, min: -4.1960305e+14 max: 2.2858488e+14 average: 7.0990082e+08
DILUPBiCG: Solving for k, Initial residual = 0.009506604, Final residual = 0.0018439062, No Iterations 1001
bounding k, min: -1.7533181e+15 max: 8.382294e+14 average: -3.8906711e+08
ExecutionTime = 19251.27 s ClockTime = 19265 s

Time = 0.00010101

Courant Number mean: 2.9411928e-05 max: 42822.926
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 0.011547178, Final residual = 4.2007322e-09, No Iterations 7
DICPCG: Solving for p_rgh, Initial residual = 0.5517749, Final residual = 0.00098472085, No Iterations 87
time step continuity errors : sum local = 1.9706388e-08, global = 1.9126112e-09, cumulative = 6.5046957e-09
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 0.00045584686, Final residual = 5.7580162e-07, No Iterations 1001
DICPCG: Solving for p_rgh, Initial residual = 0.79932465, Final residual = 0.21947454, No Iterations 1001
time step continuity errors : sum local = 4.5888733e-05, global = 2.4650819e-09, cumulative = 8.9697776e-09
DILUPBiCG: Solving for omega, Initial residual = 0.046824604, Final residual = 0.42651976, No Iterations 1001
bounding omega, min: -2.9120631e+16 max: 7.5610454e+15 average: -1.7510987e+10
DILUPBiCG: Solving for k, Initial residual = 0.10073936, Final residual = 0.053489969, No Iterations 1001
bounding k, min: -6.1933141e+14 max: 5.4698344e+14 average: -1.1146877e+09
ExecutionTime = 23333.7 s ClockTime = 23350 s

Time = 0.00010102

Courant Number mean: 0.00057248341 max: 283410.74
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 0.84933889, Final residual = 2.0178504e-09, No Iterations 9
DICPCG: Solving for p_rgh, Initial residual = 0.91110456, Final residual = 0.00098260631, No Iterations 202
time step continuity errors : sum local = 2.6226461e-07, global = -4.8494379e-08, cumulative = -3.9524602e-08
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 0.033386681, Final residual = 0.014155016, No Iterations 1001
DICPCG: Solving for p_rgh, Initial residual = 0.80383648, Final residual = 5.7958476, No Iterations 1001
time step continuity errors : sum local = 0.020399066, global = -9.6567685e-09, cumulative = -4.918137e-08
DILUPBiCG: Solving for omega, Initial residual = 0.98880096, Final residual = 11962.323, No Iterations 1001
bounding omega, min: -6.4680894e+24 max: 3.2921399e+25 average: 5.2212511e+19
DILUPBiCG: Solving for k, Initial residual = 0.014781795, Final residual = 3.0990057e-08, No Iterations 1001
bounding k, min: -4.8263648e+14 max: 5.4072665e+14 average: 1.0635891e+09
ExecutionTime = 27448.32 s ClockTime = 27467 s

Time = 0.00010103

Courant Number mean: 0.045544987 max: 5.2721582e+08
PIMPLE: iteration 1
DILUPBiCG: Solving for T, Initial residual = 0.49369191, Final residual = 7.5375708e-09, No Iterations 7
DICPCG: Solving for p_rgh, Initial residual = 0.96557631, Final residual = 0.00099907484, No Iterations 238
time step continuity errors : sum local = 3.3753698e-05, global = 7.2331754e-06, cumulative = 7.183994e-06
PIMPLE: iteration 2
DILUPBiCG: Solving for T, Initial residual = 0.88776239, Final residual = 50.198586, No Iterations 1001
DICPCG: Solving for p_rgh, Initial residual = 0.0023242099, Final residual = 1.4577883, No Iterations 1001
time step continuity errors : sum local = 171.529, global = 1.7893858e-06, cumulative = 8.9733799e-06

------------------------------------------------------------------

I'll be really glad if someone helps me dealing with this problem and getting my simulation running. Thanks.


Jubayer
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Old   June 19, 2012, 03:59
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Have you tried using different input for the divergence and laplacian schemes?

divergence as "Gauss upwind" and laplacian as "Gauss linear corrected", especially for the parts where you use k and omega. These schemes have worked for me with different simulations. If you really need to use the schemes that you have as an input now, I would start from these easier schemes and switch over to more advanced schemes step by step.
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Old   June 19, 2012, 04:29
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hello,
Your time step seems too big, since your Co number is getting higer and higer ...
Try to lower your time step, or use adaptative time stepping.

regards,
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Old   June 19, 2012, 09:46
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Jubayer
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Hi Roman,

Thanks for your advice. I'll try those schemes. However, I used simpler schemes before, but did not work. Lets hope this time it works.

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Old   June 19, 2012, 09:49
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Hi Olivier,

I thought of the time step size at first. But as you can see, I have even used 10^-09 s for this full scale simulation, lowering time step size more than that does not make sense. This made me belief that the problem is somewhere else. Thanks for your input.

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