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Fluent交流区

994 主题 4.4k 帖子
  • 3 帖子
    2k 浏览
    L

    @Ivan 速度为10 ,管径0.075m 粘度0.2 雷诺数5000多,计算误差不大昂,直接用SSTkOmega计算的,压降取充分发展段,与达西公式计算相符。WALLSHEARSTRESS也是符合的。

  • 1 帖子
    229 浏览
    L

    fluent无论设置周期边界(控制质量流率),还是速度入口压力出口,都算不出湍流,结果和层流相近,是什么原因哇。

  • VOF模型中操作密度相关问题

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    B

    老哥 您好 我也有同样的问题 可以求教您吗

  • 2 帖子
    975 浏览
    B

    感觉 VOF+LEE是不是没有考虑核态沸腾 所以不会有达到饱和温度之后温度下降那一块,而正是这一块才导致沸腾换热系数上升

  • Fluent Maxwell速度滑移和温度跳跃

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    1 帖子
    430 浏览
    E

    请问有大佬知道如何在Fluent中利用UDF添加Maxwell速度滑移和温度跳跃边界条件吗

  • 重叠网格算翼型升阻力误差很大

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    A

    7f0a7c02-1beb-40d4-8130-9ba6e44bbb4a-image.png d45554ce-7a55-414b-a667-8ccc7afa71c1-image.png
    从上至下依次为网格1,2,3。
    如图,翼型不同攻角的Cl验证,使用fluent2022r1在Re=5e5, SST k-w模型进行计算,稳态使用simple求解器,在攻角为5°的情况下,网格1(单一网格)算得的cl为0.479,网格2(使用重叠网格计算)算得的cl为0.531,网格3(单一网格,在网格2的前景网格为基础上拓展)算得的cl为0.475,文献上的cl在0.459-0.483之间,上述网格的正交性都比较好,y+=1。目前遇到的问题是不知道为什么用重叠网格后升力系数会差这么大。
    已使用过的方法:
    ①换不同的湍流模型计算,虽然结果有差异,但都在0.52-0.55区间波动
    ②改变计算域大小,从12c拓展到20c均无明显变化;改变前景网格区域大小,从d=5c拓展到d=20c(此时background为30c)均无明显变化
    ③使用不同的fluent版本(19,20,23),无明显差异
    实在找不出原因,有没有大神给小菜鸟解惑_/|o

  • 4 帖子
    3k 浏览
    A

    加一个界面delta函数就可以把

  • 密度基非稳态点火问题

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    3 帖子
    3k 浏览

    你看看反应速率有没有 是太低了 还是模型设置有问题

  • 1 帖子
    245 浏览
    W

    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

  • 2 帖子
    336 浏览
    李东岳

    理论上以及openfoam中,是可以作为interface处理的

  • 14 帖子
    8k 浏览
    Y

    @疯狂记笔记的小白 您好,现在这个问题不知您是否已经解决,我目前也遇到了这个问题,但是采用周期性边界又会破坏本身的出口条件,如您已解决,期待您的指点

  • 如何在动网格工况中如何设置移动测点

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    1 帖子
    206 浏览
    L

    请教各位:
    目前有一个6自由度运动的sloshing两相流模型,通过udf文件给定运动速度。

    需要测出壁面位置某些点的压强时程变化,以及某些区域的水位(波高)时程变化。请问该如何设置这些测点,使其与动网格区域一起运动。

  • 请教:基于FLUENT的LES模拟算不出湍流原因

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    26 帖子
    21k 浏览
    L

    @霜染丹枫 请问您找到原因了吗,我用了周期边界设置的固定压降,依旧是算到最后和层流一样了

  • Fluent大涡模拟计算充分发展的槽道湍流?

    4
    4 帖子
    2k 浏览
    L

    @liuxiaodong les计算圆管管道流动的,尝试了很多都最后变成层流了,这是为什么呢

  • 三维大变形问题用fluent动网格计算是否合适

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    6 帖子
    7k 浏览
    2

    @buaa_hgj 我也在做柔性变形,前辈您有什么经验可以指点一二吗?

  • 单元区域设置

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    1 帖子
    412 浏览
    W

    怎么能够对计算完的case设定单元区域,取得这个区域内自己想要的值

  • 过饱和度计算

    1
    1 帖子
    482 浏览
    V

    fluent自定义过饱和函数时应该用那个压力数据来计算?我的静压只有不到100pa,太小了

  • icem网格划分问题

    2
    2 帖子
    607 浏览
    李东岳

    看起来没问题呢

  • fluent计算微通道收敛不了

    1
    1 帖子
    472 浏览
    D

    针对一个高度为3mm,宽度为1mm的矩形微通道,用fluent mesh 画网格后,在入口流速为0.3 0.4 m/s时,计算都可以收敛。但是当入口流速为0.5m/s时,计算收敛不了,这可能是什么原因导致的,尝试过增加网格数量也无效

  • FLUNET 初始化失败。

    1
    1 帖子
    565 浏览
    2

    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.

    ==============================================================================

    ==============================================================================

    Node 5: Process 7224: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 11: Process 8716: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 7: Process 6588: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 8: Process 5632: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 9: Process 7040: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 10: Process 3868: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 6: Process 4756: Received signal SIGSEGV.

    ==============================================================================

    ==============================================================================

    Node 4: Process 820: Received signal SIGSEGV.

    ==============================================================================

    ===================================================================================
    = 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.