CFD中文网

以前简单看过，好像是研究表面活性剂的方法。大概是在三维曲面上用类似FVM的方法离散控制方程并求解。

在外加压力下（1.0 MPa）水进入螺旋文丘里管内，在喉部流速增大，压力降低，使液体组分中溶解空气的析出，不过由于喉部管径长度都远比空化管的大，所以压力降低至饱和蒸汽压以上。目前找到比较多空化的学习资料，但是这个由于压力没有降到饱和蒸汽压以下，所以溶解在水中的气体通过溶解气浓度差析出而不是空化的相变。网上找到的相关资料比较少，请问下有人知道这种情况在多相流模型这部分怎么设置吗（所用物理模型如图所示）。4944e90f4e8663cccb56c7acc73b26b.png

好东西好东西！！

@wwxdli 谢谢，我试一试

@mark alpha1_ 代表VOF模型中的体积分数，是一个volScalarField类型的对象。

@FluidGao 嗯嗯，感谢。

@东岳 谢谢！

测试编辑

看了一下你的模型，之所以你在相贯线处网格画不好，这主要问题在于你的几何模型——相贯线与底面相切，出现了三角区域。从而导致网格在该三角区域网格质量奇差无比。如下图所示

该问题导致出现了如下问题：

解决的办法是将底面拉伸一段距离，避免出现相贯线与底面相切即可，如下图所示
0_1536142189833_4ccfa31a-f8b8-4435-87b6-c322423cd7e1-image.png
如此，便可愉快的进行分块和关联
0_1536142304777_9fb3a5ee-3695-47f4-971f-61fe9c119d23-image.png
接着对其进行O型块划分
0_1536142342178_11fb8b28-9d22-441a-978f-e0f2d4ed1c7c-image.png
最终网格效果图如下
0_1536142436479_986e33bd-8587-4ee0-a010-5f914675e718-image.png

@lhzhu 在 如何拷贝/创建 volVectorField 在每一个时间步文件夹中 中说：

只要0目录里面有一个场文件，decomposePar 都会在processorX里面生成子区域的场文件。是不是你写的0/HAG_BC 的file header 里面的object 不是 HAG_BC ?

decomposePar 后 在“processorX” 中的 "0" 目录里有这个HAG_BC, 问题是下一时间步的时候没法创建这个HAG_BC啊，
所以会有那个error.
不知道怎么解决

就是两种液体接触的界面部分就没有办法加密啊？

不就是界面（表面）么？

@东岳 。。。多谢解答

感谢，我看了下，UserGuide里面U28说的是把scale关掉，这会导致所有的箭头长度和箭头头部大小都一样。目前从ParaView的控制面板上还找不到保持箭头头部大小不变，而箭头长度随速度大小scale的选项。

一般的工具（Matlab, matplotlib, Paraview）里面， quiver图 里面的箭头大小都跟着箭头长度一起变，所以在矢量很小时候，效果很糟糕。如下图就是Matlab里面quiver画出来的，
0_1461126738148_upload-25983765-853b-4a0a-b72b-a0ffce9f781b

不过后来找到一个比较好的办法，在latex里面使用pgfplot宏包可以解决。
比如如下代码(来自这里)

\documentclass{standalone} \usepackage{tikz} \usepackage{pgfplots} \begin{document} \begin{tikzpicture} \begin{axis}[domain=-3:3, view={0}{90}] \addplot3[blue, quiver={u={1}, v={(x-y)}, scale arrows=0.15}, -stealth,samples=20] {0}; \end{axis} \end{tikzpicture} \end{document}

可以产生画出：
alt text
可以看到箭头大小不随箭头长度改变。

各位前辈，我在进行一个压缩理想气体的仿真，使用了fluent自带的内燃机动网格来模拟活塞的上下运动，我这个三维压缩腔模型没有进出口，边界都是壁面，这个压缩腔内含有一部分的水，并且空气并不会溶解在水中。在时间步长为10e-05时，压缩腔内的体积平均空气质量会接近不变，但当时间步长为10e-04时，压缩腔内的体积平均空气质量会大幅度降低，导致计算结果出现很大的误差。谁知道这是怎么回事吗？270c7d84-3e4a-4a3b-a0eb-f03246e0389d-8022a33ca0ae4229656cf7dfbaaf2691.png
32391c80-98f4-4a1f-ad2b-be648153e223-b2e6b74bb524d804dfbf9eb5304f1082.png
bb35fd93-e478-4c6f-9769-18e0995e0a10-9d0248f522d25c2be2fd28eb600910ec.png
596b964a-bba4-41d7-8dce-e471b145cc16-cc8a6de7ae51246153c122cd626a3b9.png

谢谢...

@东岳 感谢李老师！

@两月三年 good ，好主意。我试试哈。

目前是在用重叠网格进行模拟，一个结构是固体，另一个是线弹性。用的是明渠造波，初始化总是崩溃，这是为什么呢？报错代码附在下面，感谢各位大佬抽出时间回答这个问题。
Grouping and repartitioning the fluid cell zones...

14 Stored Partitions:
P Cells I-Cells Cell Ratio Faces I-Faces Face Ratio Neighbors Load
0 52115 3581 0.069 176927 7246 0.041 5 1
1 52472 4620 0.088 162295 4236 0.026 4 1
2 54617 12093 0.221 134005 7412 0.055 9 1
3 52637 6006 0.114 169686 5664 0.033 4 1
4 52807 11023 0.209 167910 5289 0.031 6 1
5 52057 3479 0.067 162444 4597 0.028 5 1
6 52745 1693 0.032 170269 3362 0.020 2 1
7 52784 13211 0.250 163205 4296 0.026 5 1
8 52259 3566 0.068 176157 7128 0.040 5 1
9 51910 1672 0.032 160241 2070 0.013 1 1
10 51748 3480 0.067 164291 5004 0.030 3 1
11 54525 9324 0.171 134306 6166 0.046 8 1
12 51710 3562 0.069 166038 5640 0.034 4 1
13 54297 9707 0.179 133333 6836 0.051 9 1

Collective Partition Statistics: Minimum Maximum Total

Cell count 51710 54617 738683
Mean cell count deviation -2.0% 3.5%
Partition boundary cell count 1672 13211 87017
Partition boundary cell count ratio 3.2% 25.0% 11.8%

Face count 133333 176927 2200909
Mean face count deviation -16.7% 10.5%
Partition boundary face count 2070 7412 40198
Partition boundary face count ratio 1.3% 5.5% 1.8%

Partition neighbor count 1 9

Partition Method Metis
Stored Partition Count 14

Overset partition statistics:
P Cells Solve-cells Dead-cells
0 52115 58811 0
1 52472 52274 66
2 54617 56753 617
3 52637 54720 391
4 52807 46085 6296
5 52057 52626 0
6 52745 55832 0
7 52784 43070 6359
8 52259 58396 0
9 51910 51910 0
10 51748 53430 0
11 54525 59651 261
12 51710 54199 0
13 54297 58997 228

Overset Partition Statistics: Minimum Maximum Total

Cell count 51710 54617 738683
Mean cell count deviation -2.0% 3.5%

Solve cell count 43070 59651 756754
Mean solve cell count deviation -20.3% 10.4%

Dead cell count 0 6359 14218
Mean dead cell count deviation -100.0% 526.1%

Partition Method Metis
Stored Partition Count 14

Done.

10422 partition interfaces of the 215044 cells aspect ratio > 5 545456 groups for partitioning (including overlaps) Merging groups across partitions: 1 99888 2 8996 3 2718 4 599 5 112 6 20 7 2 8 0 Partition 535235 groups out of 738683 cells 183 partition interfaces of the 215044 cells aspect ratio > 5

Grouping and repartitioning the solid cell zones...

14 Stored Partitions:
P Cells I-Cells Cell Ratio Faces I-Faces Face Ratio Neighbors Load
0 3081 778 0.253 163329 1521 0.009 4 1
1 3081 814 0.264 163934 1432 0.009 5 1
2 3089 845 0.274 129565 7700 0.059 11 1
3 3076 819 0.266 164712 1583 0.010 3 1
4 3080 832 0.270 164935 1464 0.009 6 1
5 3079 829 0.269 162882 1455 0.009 6 1
6 3077 1026 0.333 163326 1996 0.012 7 1
7 3089 795 0.257 165081 1535 0.009 4 1
8 3092 928 0.300 163821 1637 0.010 5 1
9 3093 884 0.286 160599 1611 0.010 5 1
10 3090 761 0.246 161874 1493 0.009 4 1
11 3075 806 0.262 127548 7289 0.057 9 1
12 3097 868 0.280 162126 1544 0.010 5 1
13 3098 319 0.103 126305 4986 0.039 6 1

Collective Partition Statistics: Minimum Maximum Total

Cell count 3075 3098 43197
Mean cell count deviation -0.3% 0.4%
Partition boundary cell count 319 1026 11304
Partition boundary cell count ratio 10.3% 33.3% 26.2%

Face count 126305 165081 2133715
Mean face count deviation -18.9% 6.0%
Partition boundary face count 1432 7700 46322
Partition boundary face count ratio 0.9% 5.9% 2.2%

Partition neighbor count 3 11

Partition Method Metis
Stored Partition Count 14

Overset partition statistics:
P Cells Solve-cells Dead-cells
0 3081 55196 0
1 3081 55355 66
2 3089 54741 617
3 3076 54989 391
4 3080 47373 6296
5 3079 55136 0
6 3077 55822 0
7 3089 46159 6359
8 3092 55351 0
9 3093 55003 0
10 3090 54838 0
11 3075 56138 261
12 3097 54807 0
13 3098 55846 228

Overset Partition Statistics: Minimum Maximum Total

Cell count 3075 3098 43197
Mean cell count deviation -0.3% 0.4%

Solve cell count 46159 56138 756754
Mean solve cell count deviation -14.6% 3.9%

Dead cell count 0 6359 14218
Mean dead cell count deviation -100.0% 526.1%

Partition Method Metis
Stored Partition Count 14

Done.

42 partition interfaces of the 1073 cells aspect ratio > 5 43150 groups for partitioning (including overlaps) Merging groups across partitions: 1 6 2 0 Partition 43147 groups out of 43197 cells *** Subcommunicators recreated (11/14)! *** 565 partition interfaces of the 1073 cells aspect ratio > 5 Migrating partitions to compute-nodes.

Node 1: Process 14244: Received signal SIGSEGV.

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Node 13: Process 4932: Received signal SIGSEGV.

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Node 5: Process 7224: Received signal SIGSEGV.

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Node 11: Process 8716: Received signal SIGSEGV.

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Node 7: Process 6588: Received signal SIGSEGV.

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Node 8: Process 5632: Received signal SIGSEGV.

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Node 9: Process 7040: Received signal SIGSEGV.

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Node 10: Process 3868: Received signal SIGSEGV.

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Node 6: Process 4756: Received signal SIGSEGV.

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Node 4: Process 820: Received signal SIGSEGV.

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===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 0 PID 13864 RUNNING AT DESKTOP-RDMJC80
= EXIT STATUS: -1 (ffffffff) ===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 2 PID 12200 RUNNING AT DESKTOP-RDMJC80
= EXIT STATUS: -1 (ffffffff)

The fl process could not be started.

这几天在看有限体积法的书，大佬的论文、《数值传热学》和 《The FVM inCFD OpenFOAM..Matlab》都看了，逛论坛发现都在推荐《Computational Methods for Fluid Dynamics》这本；去SpringerLink一搜正好今年出了新版，网上资源好像还不多，在这里分享一下： 点击下载

感谢管理员，

这个minimal example 不写文件确实是因为我忘了加上runTime.write():cold_sweat: 。它并不能重现我原来solver里面的问题。我再找找原因。