How to assign values to halos in parallel

Zhen ZHANG · October 13, 2021, 10:05

Hi all,

I want to read the turbulent Prandtl number at each grid point from a file, but I got some problem in the parallel calculation.

I basically mimic CSolver::Read_SU2_Restart_ASCII. Loop for the global point index, and if geometry->GetGlobal_to_Local_Point(iPoint_Global) > -1, set the value to a VectorType Prt_Val in the variable class.

The series calculation goes well, but the parallel one diverges. I find that the Prandtl number is assigned to the Domain part of the Prt_Val but not to the halo part. So the turbulent Prandtl number keeps the initial value at some points, which leads to the divergence.

Please help me to solve this problem. If I am not clear, please let me know.

Thanks a lot!

Zhen

TKatt · October 14, 2021, 12:19

Hi,

as a first shot I would guess you are missing some InitiateComms and CompleteComms calls on PRANDTL_TURB. That should take care of that communication once the stuff is read for each rank correctly.

See e.g. CFVMFlowSolverBase.inl in the LoadRestart_impl where first the correct solution (e.g. rho, rho*u, rho*v, ... for compressible) is read in their respective container and then SOLUTION is then communicated around over the ranks.

There are implementations for a multitude of quantities but of course not PRANDTL_TURB, so that is what you would have to implement yourself.

When you work so closely on the code, you might want to use github a bit more. This is usually the case where coding related questions are meant to go ... but of course it is not an issue to post here

Best Tobi

Zhen ZHANG · October 15, 2021, 00:43

Hi Tobi,

It helps and is very convenient to implement. Very nice design.

Thank you for your help!

As for Github, I will try to use it. But it is a little hard to visit it in China

Zhen

October 13, 2021, 10:05	How to assign values to halos in parallel	#1
Zhen ZHANG Member Zhen ZHANG Join Date: Jun 2018 Location: Beijing, China Posts: 56 Rep Power: 8	Hi all, I want to read the turbulent Prandtl number at each grid point from a file, but I got some problem in the parallel calculation. I basically mimic CSolver::Read_SU2_Restart_ASCII. Loop for the global point index, and if geometry->GetGlobal_to_Local_Point(iPoint_Global) > -1, set the value to a VectorType Prt_Val in the variable class. The series calculation goes well, but the parallel one diverges. I find that the Prandtl number is assigned to the Domain part of the Prt_Val but not to the halo part. So the turbulent Prandtl number keeps the initial value at some points, which leads to the divergence. Please help me to solve this problem. If I am not clear, please let me know. Thanks a lot! Zhen

October 14, 2021, 12:19		#2
TKatt Member na Join Date: Jul 2018 Posts: 90 Rep Power: 8	Hi, as a first shot I would guess you are missing some InitiateComms and CompleteComms calls on PRANDTL_TURB. That should take care of that communication once the stuff is read for each rank correctly. See e.g. CFVMFlowSolverBase.inl in the LoadRestart_impl where first the correct solution (e.g. rho, rhou, rhov, ... for compressible) is read in their respective container and then SOLUTION is then communicated around over the ranks. There are implementations for a multitude of quantities but of course not PRANDTL_TURB, so that is what you would have to implement yourself. When you work so closely on the code, you might want to use github a bit more. This is usually the case where coding related questions are meant to go ... but of course it is not an issue to post here Best Tobi Last edited by TKatt; October 15, 2021 at 05:34.

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October 15, 2021, 00:43		#3
Zhen ZHANG Member Zhen ZHANG Join Date: Jun 2018 Location: Beijing, China Posts: 56 Rep Power: 8	Hi Tobi, It helps and is very convenient to implement. Very nice design. Thank you for your help! As for Github, I will try to use it. But it is a little hard to visit it in China Zhen