OpenFOAM散热器自然散热问题

[Do1975]

@李东岳 李老师，我尝试把迭代步数增加，能达到我想要的效果了（散热器颜色均匀），但是出现了另外的问题，现在迭代步数增加到30000步了，虽然温度云图已经稳定了，但是颜色条一直往上跑（附gif图），没有收敛的趋势，或许需要继续增加迭代步数。
这也带来两个疑问：
1）会不会是控制方程写错或边界条件写错导致不收敛；
2）这么多的迭代步数求解时间很长，即使用了并行计算（28核），也需要将近一小时的计算时间，显然不利于后续开展优化计算。有什么可以加快迭代计算方法吗？还是说自然散热求解本身就需要这么长的时间。我用商软计算只需要几分钟（数百次迭代）就可以计算出来了。

附图：温度变化动图

[李东岳]

看起来是设置的问题，如果你能把你的算例发上来，我可以给你看看。

[Do1975]

@李东岳 谢谢李老师，附件是我的Case，麻烦老师您帮忙看看哪边出问题了。
代码的一些说明：
1）几何模型中Heatsink是通过读取0文件夹下gamma场进行生成的；
2）UEqn.H代码中增加了源项，其中si是阻流系数，用来区分Heatsink（si=alphamax）和Air（si=0）；
3）TEqn.H代码中的DT通过插值方式分别在Heatsink和Air区域赋予不同的值。

Case.zip
附件：自然散热Case

[李东岳]

明天给你看一下 老铁

[Do1975]

@李东岳 好的，麻烦李老师了。
说明下，OpenFOAM使用的是6.0版本。
我把迭代次数增加到50000步，也还是出现一样的问题 。

[李东岳]

你这里面有个自己写的代码，需要用你写的代码来跑么

[Do1975]

@李东岳 应该直接编译就可以跑了

[李东岳]

自己写的代码bug不好判断，无法判断是代码的bug，还是算例的bug，我只能用openfoam官方的求解器跑算例，然后看你算例设置是否有问题。你有官方求解器能跑的算例么？

[Do1975]

@李东岳 这个没有，因为Heatsink的引入是通过代码实现的，所以我是基于官方求解器上进行添加的。大部分都没有动原来官方求解器代码。
另外一个考虑是，官方使用的是湍流模型，而我使用的是层流模型，有点不一样。

[李东岳]

你有没有用过chtMultiRegionFoam，可以处理多域传热问题

[Do1975]

@李东岳 李老师，这个求解器我还没用过。
目前我是按拓扑优化的处理方式来计算多域传热问题，有点类似《无痛苦N-S方程笔记》中Darcy-Brinkman-Stokes 方程的处理方式。
【在我的模型中，源项为si=-alpha*u，其中alpha由gamma来控制，gamma=1代表Air，gamma=0代表Heatsink】

图1 Darcy-Brinkman-Stokes介绍

图2 自然散热拓扑优化模型[source: Applied Energy 314 (2022) 118984]

[李东岳]

文章下载不下来。不知道你的导热系数DT是不是有个明确的固体气体分界。

[Do1975]

好像找到问题了。
我把tolerance从1e-6改为1e-5计算就可以收敛了，到100000步的时候温度不再发生变化。
但是想请教下各位老师，tolerance这种一般如何设置呢？有什么依据来源？还是说只能根据模型来进行调试？

图1 fvSolution设置

[Do1975]

@李东岳 李老师，是明确的。导热系数使用的是Air(0.024)，Heatsink(237)，并且为常值，不随温度进行变化。

[李东岳]

瞬态算例应该把你的relTol去掉。你加上relTol，那就是满足relTol就跳出了。

[Do1975]

@李东岳 李老师，我跑了下去掉relTol，和没有去掉的相比，跑出来是一样的。

[李东岳]

把你的log用文本的形式贴一下

[Do1975]

DILUPBiCGStab:  Solving for Ux, Initial residual = 2.52879e-12, Final residual = 2.52879e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 4.759e-13, Final residual = 4.759e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 1.12742e-08, Final residual = 4.99184e-09, No Iterations 1
time step continuity errors : sum local = 9.26478e-12, global = -1.95551e-19, cumulative = -1.76865e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 4.08769e-12, Final residual = 4.08769e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 7.69458e-13, Final residual = 7.69458e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 3.05161e-09, Final residual = 3.05161e-09, No Iterations 0
time step continuity errors : sum local = 5.66373e-12, global = -3.93401e-18, cumulative = -1.76869e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 3.31261e-12, Final residual = 3.31261e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 6.5252e-13, Final residual = 6.5252e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 3.57218e-09, Final residual = 3.57218e-09, No Iterations 0
time step continuity errors : sum local = 6.6299e-12, global = -3.50639e-18, cumulative = -1.76873e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 2.81837e-12, Final residual = 2.81837e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 5.66173e-13, Final residual = 5.66173e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 5.30704e-09, Final residual = 5.30704e-09, No Iterations 0
time step continuity errors : sum local = 9.84979e-12, global = 8.65936e-19, cumulative = -1.76872e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 2.48061e-12, Final residual = 2.48061e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 5.01799e-13, Final residual = 5.01799e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 7.25581e-09, Final residual = 7.25581e-09, No Iterations 0
time step continuity errors : sum local = 1.34667e-11, global = -7.49204e-18, cumulative = -1.76879e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 2.20698e-12, Final residual = 2.20698e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 4.5362e-13, Final residual = 4.5362e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 8.96308e-09, Final residual = 8.96308e-09, No Iterations 0
time step continuity errors : sum local = 1.66353e-11, global = -2.10879e-18, cumulative = -1.76882e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 1.98591e-12, Final residual = 1.98591e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 4.17482e-13, Final residual = 4.17482e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 1.04578e-08, Final residual = 4.41247e-09, No Iterations 1
time step continuity errors : sum local = 8.18947e-12, global = -6.46356e-18, cumulative = -1.76888e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 4.01256e-12, Final residual = 4.01256e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 7.47198e-13, Final residual = 7.47198e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 2.55585e-09, Final residual = 2.55585e-09, No Iterations 0
time step continuity errors : sum local = 4.74361e-12, global = -9.69952e-19, cumulative = -1.76889e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 3.26589e-12, Final residual = 3.26589e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 6.35781e-13, Final residual = 6.35781e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 3.36828e-09, Final residual = 3.36828e-09, No Iterations 0
time step continuity errors : sum local = 6.25147e-12, global = -2.50355e-18, cumulative = -1.76892e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 2.81174e-12, Final residual = 2.81174e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 5.53575e-13, Final residual = 5.53575e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 5.49292e-09, Final residual = 5.49292e-09, No Iterations 0
time step continuity errors : sum local = 1.01948e-11, global = 1.63108e-18, cumulative = -1.7689e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 2.47921e-12, Final residual = 2.47921e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 4.92095e-13, Final residual = 4.92095e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 7.48208e-09, Final residual = 7.48208e-09, No Iterations 0
time step continuity errors : sum local = 1.38866e-11, global = -2.32211e-18, cumulative = -1.76892e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 2.20866e-12, Final residual = 2.20866e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 4.45864e-13, Final residual = 4.45864e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 9.21963e-09, Final residual = 9.21963e-09, No Iterations 0
time step continuity errors : sum local = 1.71115e-11, global = 1.08066e-18, cumulative = -1.76891e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 1.99261e-12, Final residual = 1.99261e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 4.10956e-13, Final residual = 4.10956e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 1.07404e-08, Final residual = 4.80571e-09, No Iterations 1
time step continuity errors : sum local = 8.91934e-12, global = -3.39057e-18, cumulative = -1.76895e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 4.25332e-12, Final residual = 4.25332e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 7.89251e-13, Final residual = 7.89251e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 2.91529e-09, Final residual = 2.91529e-09, No Iterations 0
time step continuity errors : sum local = 5.41074e-12, global = 8.02024e-19, cumulative = -1.76894e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 3.4724e-12, Final residual = 3.4724e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 6.68648e-13, Final residual = 6.68648e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 3.84833e-09, Final residual = 3.84833e-09, No Iterations 0
time step continuity errors : sum local = 7.14245e-12, global = 4.1512e-19, cumulative = -1.76893e-13
DILUPBiCGStab:  Solving for Ux, Initial residual = 3.01207e-12, Final residual = 3.01207e-12, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 5.79223e-13, Final residual = 5.79223e-13, No Iterations 0
DILUPBiCGStab:  Solving for T, Initial residual = 9.9999e-06, Final residual = 9.9999e-06, No Iterations 0
DICPCG:  Solving for p_rgh, Initial residual = 6.1755e-09, Final residual = 6.1755e-09, No Iterations 0
time step continuity errors : sum local = 1.14616e-11, global = -6.35775e-18, cumulative = -1.769e-13
Time = 120000

ExecutionTime = 834.37 s  ClockTime = 834 s

[Do1975]

算到后面No Iterations都显示的0了

[李东岳]

瞬态还是稳态求解器？瞬态的话为什么没有时间步信息，稳态的话好像有时间项。没看明白老铁。