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OpenFOAM交流区

5.4k Topics 31.9k Posts
  • 2 Posts
    2k Views
    李东岳

    @xpc um, 我做surfaceLIC还没遇到过这个问题,也就不知道咋整了,看看别的大佬怎么说

  • 槽道湍流底部微吹

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    43 Posts
    35k Views
    2

    @李东岳 好的李老师

  • 7 Posts
    5k Views
    H

    Fine. Give me more details about performance. Reducing switch is expected to reduce communication delay which is benifit to mpi. To what extend will the smaller delay improve the performance when running CFD application. Is this another advantage of ring topology infiniband network?

    The performance improvement due to the reduced communication delay in a ring topology compared to a star topology depends largely on the specifics of your CFD application.

    With the InfiniBand protocols, the primary factor that contributes to the delay is not the time it takes for the packet to traverse the physical network (which is typically less than a few microseconds), but the time it takes for the packet to get through the software stack. The overhead of software in sending and receiving messages can be a significant component of the total latency.

    MPI-based CFD applications often require large scale, synchronized computing. If your application often needs to exchange small amounts of data between all nodes (such as boundary values or synchronization barriers), then minor latency improvements might accumulate and contribute to significant overall performance improvement.

    However, if your CFD application is structured so that most of the time is spent in computation, and communication is relatively infrequent (typical for methods where each node can work on a discrete part of the problem for much of the time), then the improvement might be marginal.

    Furthermore, if your CFD application is using collective communication, like MPI_Bcast or MPI_Reduce, or if it's using non-blocking sends/receives, then it may be intelligent enough to take advantage of the network topology to minimise communication delays.

    So, it can potentially be an advantage of ring topology, but the magnitude of this advantage is highly dependent on the specifics of your CFD code. Thorough testing will be necessary to calculate the potential benefit in your own case.

  • 3 Posts
    2k Views
    李东岳

    一楼那个好像还没有。目前还没有哪种算法可以处理类似这种某个变量依附于某个变量的东西。OpenFOAM这面组分就是定义了个Y,如果你要某个变量依附于Y,那就是重新定义一个方程,但是传输的时候,要完完全全的按照Y的求解植入,要不然会不一致。

  • 3 Posts
    2k Views
    杨英狄

    @杨英狄 感谢感谢!

  • interfaceHeight函数运行过慢

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    4 Posts
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    李东岳

    @tidedrinker :146: :146: :146: :146:

  • ercoftac泵,OpenFOAM可压缩算例

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    1 Posts
    2k Views
    李东岳

    稳态算例点击下载 | 瞬态算例点击下载

    瞬态算例下载地址

  • 效率公式植入openfoam的问题

    1
    1 Posts
    1k Views
    G

    大家好,我将文献中的公式植入到foam—extend4.1的force.C文件中发现算出来的数据与文献的数据相差较大,下面是我的代码和公式,希望有大佬帮我看一下我编的是否正确。ps:我用的是浸没边界法,不知道这个速度这样获取可以不。
    be1e4612d51ceea1f453b513f11f757.png
    1.png
    2.png ```

  • lagrangian库如何跟踪一个颗粒

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    11 Posts
    8k Views

    @lrl3512 这你就遇到了难点,比如parcel穿过processor怎么办?你想想有没有其他的方法能单独对每个parcel赋值?

  • 求测试GPU算力的case

    2
    2 Posts
    2k Views
    李东岳

    https://www.cfd-china.com/topic/6237

    你可以看看这个

  • 3 Posts
    3k Views
    G

    @wuyukai 请问你这个问题解决了吗?我遇到同样的问题

  • 搅拌罐的出口边界设置问题

    2
    2 Posts
    2k Views

    另外有没有可能是这类边界只适用于稳态求解器来忽略气体鼓入之后移动到液面这一过程的影响,对于multiphaseEulerFoam这种瞬态求解器而不适用呢?

  • 带挡板的晃荡

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    1 Posts
    1k Views
    李东岳

    直接Allrun开算,OpenFOAM-10适配

    baffleVOF.tar.xz

    微信图片_20230728160847.png

  • 再请教2个集群问题

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    19 Posts
    17k Views
    C

    @leilei ls试了下和在外面是一样的,pwd看了下是我进singularity之前的路径。不方便贴图上来,还请见谅哈。

  • probes文件夹合并

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    5 Posts
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    李东岳

    没啥影响

  • 20 Posts
    20k Views
    李东岳

    运动粘度用sutherland定律来计算,也就是在温度高的地方粘性大,相乘的话也就是在温度高的地方耗散率相对比较大,这样是合理的吗?

    我重新核查了一下$\epsilon$的定义,这个看起来就是层流粘度。如果这样说的话,看起来就是跟粘度相关的变量。这个我目前也不能确定,你最好查一下相关的文献,是不是这样的。也告诉我一下

    https://www.cfd-online.com/Wiki/Turbulence_dissipation_rate

    你这个确实是个好问题,需要严肃的研究一下

  • 1 Posts
    955 Views
    J

    请问rigidBodyMotionState不是应该输出刚体的质心运动位置速度等参数吗?
    7adc20a4-dcb7-46c4-8134-c0d63734b4a3-image.png

    a86b7043-7e19-40c2-bc34-8d886d941bb8-image.png

    这些q、qDot和qDot怎么理解啊?
    若能回复十分感激。

  • paraview输出尾涡

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    7 Posts
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    李东岳

    @快乐的山炮 应该是按照等值面画的涡量,然后显示的是SVV

  • 3 Posts
    2k Views
    J

    @田畔的风 好的,谢谢老师。我试一试

  • 气液固三相模拟k-epsilon发散

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    3 Posts
    3k Views
    李东岳

    湍流模型,以及drag模型需要调试一下,这个就是方程奇异的问题。另外fvSolution那面可以不挂预条件试一下