Some questions about the MRT-LBM code

[HPL001]

Dear Dr. Yang:

I have read the LBM related code written by taichi. Thank you very much for providing such a good code. I would like to express my thanks and respect to you. However, I have some unclear questions about the code, so I would like to consult you by email. I am looking forward to your reply very much.

1. In line 236 of LBM_3D_SinglePhase_Solver.py, I noticed that you adopted the external force format proposed by Guo et al. However, in this line, according to the literature, the division sign before 3.0 and 9.0 seems to be the multiplication sign, I wonder if my understanding is correct.

2. I replaced just the meq_vec function in LBM_3D_SinglePhase_Solver.py with one of the parameters mentioned in other blog, but the calculation is not correct.

3. Some parameters you used in MRT-LBM, such as M matrix and meq_vec function calculation, are specifically from which literature? I hope you can give me some advice.

Just learning LBM, a little confused, looking forward to getting teacher's advice, thank you.

[yjhp1016]

Hi, thanks for your interest.

For MRT scheme, I think I used matrix from Jonas Tolke ( https://scholar.google.co.uk/citations?user=pqvNBG4AAAAJ&hl=en&oi=sra), the multiphase MRT is implementation of this paper: https://www.academia.edu/download/49402024/Prediction_of_capillary_hysteresis_in_po20161006-2253-ac2ugg.pdf

For simple phase paper, it should be from another paper of Jonas Tolke.

For other questions regarding code modification/debugging, I'm afraid I don't have time on that right now... Hopefully you find a solution soon.

Thanks,

Jianhui

On Sat, 12 Oct 2024 at 17:51, HPL001 @.***> wrote:

Dear Dr. Yang:

I have read the LBM related code written by taichi. Thank you very much for providing such a good code. I would like to express my thanks and respect to you. However, I have some unclear questions about the code, so I would like to consult you by email. I am looking forward to your reply very much.

1.

In line 236 of LBM_3D_SinglePhase_Solver.py, I noticed that you adopted the external force format proposed by Guo et al. However, in this line, according to the literature, the division sign before 3.0 and 9.0 seems to be the multiplication sign, I wonder if my understanding is correct. 2.

I replaced just the meq_vec function in LBM_3D_SinglePhase_Solver.py with one of the parameters mentioned in other blog, but the calculation is not correct. 3.

Some parameters you used in MRT-LBM, such as M matrix and meq_vec function calculation, are specifically from which literature? I hope you can give me some advice.

Just learning LBM, a little confused, looking forward to getting teacher's advice, thank you.

— Reply to this email directly, view it on GitHub https://github.com/yjhp1016/taichi_LBM3D/issues/34, or unsubscribe https://github.com/notifications/unsubscribe-auth/AJEDKQHW5MM2MRDJAYLGPALZ3FHRRAVCNFSM6AAAAABP2SBIIKVHI2DSMVQWIX3LMV43ASLTON2WKOZSGU4DGMRVGQ2DCOA . You are receiving this because you are subscribed to this thread.Message ID: @.***>

[HPL001]

Thank you for your reply. I will continue my research based on your help. Thank you very much.

[HPL001]

杨博士您好，思考了一段时间，仍有些问题难以解决，很抱歉再次打扰您。我注意在Guo格式的力计算中，您采用了如图形式。我疑惑地是原文中需要除Cs2和Cs4是如何处理的呢？此外，松弛时间的选择，您给了两种形式，这个该依据什么来选择呢？这导致我在采用您单相流中泊肃叶流动的相关case时并不能与解析解验证上。盼望得到您的回复。

[yjhp1016]

我应该都使用了Cs=1处理的，没有考虑更特殊的情形。 另外有可能在代码迭代的过程我尝试过好几篇文章，中间有些参数可能混起来了，你可能需要找一篇你想实现的文章，照着它更改参数就行。框架不用动，只需要保证各个参数都是匹配的就行

On Fri, 18 Oct 2024 at 10:32, HPL001 @.***> wrote:

杨博士您好，思考了一段时间，仍有些问题难以解决，很抱歉再次打扰您。我注意在Guo格式的力计算中，您采用了如图形式。我疑惑地是原文中需要除Cs2和Cs4是如何处理的呢？此外，松弛时间的选择，您给了两种形式，这个该依据什么来选择呢？这导致我在采用您单相流中泊肃叶流动的相关case时并不能与解析解验证上。盼望得到您的回复。 _20241018172954.png (view on web) https://github.com/user-attachments/assets/dd988746-c939-4541-ab26-efa3b44b2d78

— Reply to this email directly, view it on GitHub https://github.com/yjhp1016/taichi_LBM3D/issues/34#issuecomment-2421969384, or unsubscribe https://github.com/notifications/unsubscribe-auth/AJEDKQE55KEXU4DZ36QQKDTZ4DIUDAVCNFSM6AAAAABP2SBIIKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDIMRRHE3DSMZYGQ . You are receiving this because you commented.Message ID: @.***>

[HPL001]

非常感谢您的回复，我调整了一些参数，已经可以运行了。