OpenFOAM散热器自然散热问题

Do1975

@李东岳李老师，这是计算初始的log

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
Build  : 6-fa1285188035
Exec   : NaturalConvection -parallel
Date   : May 22 2024
Time   : 23:08:20
Host   : "ubuntu"
PID    : 5459
I/O    : uncollated
Case   : /home/hyc2/OpenFOAM_RUN/0_SIMP/NaturalConvection/Parallel_version/Case/app2
nProcs : 28
Slaves : 
27
(
"ubuntu.5460"
"ubuntu.5461"
"ubuntu.5462"
"ubuntu.5463"
"ubuntu.5464"
"ubuntu.5465"
"ubuntu.5466"
"ubuntu.5467"
"ubuntu.5468"
"ubuntu.5469"
"ubuntu.5470"
"ubuntu.5471"
"ubuntu.5472"
"ubuntu.5473"
"ubuntu.5474"
"ubuntu.5475"
"ubuntu.5476"
"ubuntu.5477"
"ubuntu.5478"
"ubuntu.5479"
"ubuntu.5480"
"ubuntu.5481"
"ubuntu.5482"
"ubuntu.5483"
"ubuntu.5484"
"ubuntu.5485"
"ubuntu.5486"
)

Pstream initialized with:
    floatTransfer      : 0
    nProcsSimpleSum    : 0
    commsType          : nonBlocking
    polling iterations : 0
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0


SIMPLE: No convergence criteria found

Reading thermophysical properties

Reading field gamma: Generate Heatsink

Reading field T

Reading field p_rgh

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Creating turbulence model

Selecting turbulence model type laminar
Selecting laminar stress model Stokes
Reading field alphat


Reading g

Reading hRef
Calculating field g.h

No MRF models present

Radiation model not active: radiationProperties not found
Selecting radiationModel none
No finite volume options present

Starting time loop

DILUPBiCGStab:  Solving for Ux, Initial residual = 2.26016e-12, Final residual = 2.26016e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 5.55456e-12, Final residual = 5.55456e-12, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 1, Final residual = 4.19741e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.9978, Final residual = 8.46846e-09, No Iterations 285
time step continuity errors : sum local = 3.21147e-18, global = 3.8703e-28, cumulative = 3.8703e-28
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.259229, Final residual = 2.413e-06, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.247759, Final residual = 1.26753e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.3081, Final residual = 1.17625e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.429708, Final residual = 9.40879e-09, No Iterations 282
time step continuity errors : sum local = 7.68457e-15, global = -3.36581e-20, cumulative = -3.36581e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.198942, Final residual = 1.74793e-06, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.138458, Final residual = 1.76607e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.183205, Final residual = 6.90531e-07, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.223346, Final residual = 8.62887e-09, No Iterations 281
time step continuity errors : sum local = 7.66024e-15, global = 6.73161e-20, cumulative = 3.36581e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.151191, Final residual = 1.30986e-06, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0986773, Final residual = 1.98811e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.130488, Final residual = 8.37963e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.156401, Final residual = 9.06892e-09, No Iterations 280
time step continuity errors : sum local = 7.64333e-15, global = -3.75832e-28, cumulative = 3.36581e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.120235, Final residual = 1.04164e-06, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.092295, Final residual = 1.95079e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.101424, Final residual = 6.04994e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.12596, Final residual = 9.2546e-09, No Iterations 279
time step continuity errors : sum local = 7.5916e-15, global = -3.33951e-20, cumulative = 2.62952e-22
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.0985023, Final residual = 8.79964e-07, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0805056, Final residual = 1.83179e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.0830071, Final residual = 4.77933e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.110625, Final residual = 9.08261e-09, No Iterations 279
time step continuity errors : sum local = 7.66431e-15, global = 6.32595e-28, cumulative = 2.62953e-22
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.0821466, Final residual = 7.69235e-07, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0689735, Final residual = 1.70448e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.0702824, Final residual = 4.13367e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.105393, Final residual = 8.86695e-09, No Iterations 279
time step continuity errors : sum local = 7.71868e-15, global = 3.36581e-20, cumulative = 3.3921e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.0699188, Final residual = 6.85981e-07, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0600396, Final residual = 1.58394e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.060963, Final residual = 3.73141e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.107299, Final residual = 9.0363e-09, No Iterations 278
time step continuity errors : sum local = 7.69957e-15, global = 3.36581e-20, cumulative = 6.75791e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.0607945, Final residual = 6.21142e-07, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0531695, Final residual = 1.47411e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.0538401, Final residual = 3.43971e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.111654, Final residual = 9.04241e-09, No Iterations 278
time step continuity errors : sum local = 7.78919e-15, global = -2.62945e-22, cumulative = 6.73161e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.0537628, Final residual = 5.69473e-07, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0478181, Final residual = 1.37697e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.0482197, Final residual = 3.21353e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.117545, Final residual = 9.42683e-09, No Iterations 277
time step continuity errors : sum local = 7.72011e-15, global = -3.33951e-20, cumulative = 3.3921e-20
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.0483543, Final residual = 5.27961e-07, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.0434155, Final residual = 1.29181e-06, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 0.0436704, Final residual = 3.07378e-06, No Iterations 2
DICPCG:  Solving for p_rgh, Initial residual = 0.124436, Final residual = 9.52381e-09, No Iterations 277
time step continuity errors : sum local = 7.77171e-15, global = -2.62968e-22, cumulative = 3.36581e-20

李东岳

DILUPBiCGStab:  Solving for Ux, Initial residual = 0.259229, Final residual = 2.413e-06, No Iterations 1

你这个看起来并没有读取relTol 0.1的信息。正常应该是这样类似：

DILUPBiCGStab:  Solving for Ux, Initial residual = 0.259229, Final residual = 0.259229/10

咋回事就不知道了，需要详细debug。所有变量都没有读取relTol。不过无所谓。反正是瞬态。

另外，你的瞬态求解器里面，每个方程压力方程只求解一次，这个要最少2次。

Do1975

@李东岳好的，谢谢李老师
我试试在求解器中把压力计算循环两次看看效果。

Do1975

好像没法直接循环两次，我通过下述方式处理计算直接报错了，有其他方式可以保证压力方程求解2次嘛？

 for(int i=0;i<2;i++)
{
     #include "pEqn.H"
}

李东岳

压力循环两次不是简单的循环两次，这里面涉及到速度压力耦合求解。类似那种for循环两次压力方程，这是不可以的。你最好找个现有的pimplefoam来植入你的方程。而不是自己写。

Do1975

问题已解决。
经过调试，自己写的求解器没有问题，fvSolution的relaxationFactors需要修改。
原本relaxationFactors设置为：

relaxationFactors
{
    fields
    {
        p_rgh           0.7;
    }
    equations
    {
        U               0.3;
        T               0.5;
        "(k|epsilon|R)" 0.7;
    }
}

将p_rgh改为0.3，U改为0.7，去掉T的放缩因子，修改后如下：

relaxationFactors
{
    fields
    {
        p_rgh           0.3;
    }
    equations
    {
        U               0.7;
        "(k|epsilon|R)" 0.7;
    }
}

计算后结果如下图所示（热流密度修改为1.0，迭代步数200）：

李东岳

在一个时间步里面压力循环执行一次从理论上来说也是不正常的。
瞬态求解器不能添加松弛因子。

Do1975

@李东岳在 OpenFOAM散热器自然散热问题中说：

在一个时间步里面压力循环执行一次从理论上来说也是不正常的。

瞬态求解器不能添加松弛因子。

李老师，有个不解的地方，为什么执行一次不正常，像simplefoam之类的求解器，每个时间步内压力循环执行不也是只有一次吗？
另外程序是基于buoyantBoussinesqSimpleFoam求解器进行修改的，应该属于稳态求解。

李东岳

瞬态跟稳态不一样。稳态求解器可以执行一次。如果是稳态那么没问题。

Do1975

@李东岳好勒好勒，谢谢李老师回答。感觉又接触到很多没学过的知识了

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OpenFOAM散热器自然散热问题