Author Topic: Trillinos FS Kratos Solver stuck  (Read 793 times)

camaosos

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Trillinos FS Kratos Solver stuck
« on: December 27, 2016, 05:57:18 PM »
Dear Kratos team,

I'm running a Fluid-Structure interaction simulation in parallel. It gets stuck in the solver (maybe in the pressure solving) and does not continue in the second time step. It seems to happen most of the times (but not all the times).

I increased the verbosity to 2 and it suddenly stops after the fractional velocity iterations (I'm using the Trilinos fractional step solver by the way) and does not throw any error. I'm using 1339309 mesh nodes and 12 processors now in the fluid for this problem. Have you ever experienced this problem before?

This is the "tail" of the Kratos output:

Fractional velocity relative error: 1.12527e-07
Fractional velocity converged in 2 iterations.
Calculating Pressure.
 
CurrentTime = 0.005
System Construction Time : 0
Building Time : 4.87
"entering in the solver" : entering in the solver



Thanks in advance,
Carlos

jcotela

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Re: Trillinos FS Kratos Solver stuck
« Reply #1 on: December 28, 2016, 11:29:25 AM »
Dear Carlos,
If this is a problem that only happens sometimes, it may be related to parallelization issues. How are you setting the environment to run the case? Since you are using the MPI-based trilinos solvers, can you try setting the environment variable OMP_NUM_THREADS=1 to disable OpenMP parallelism?

If this does not solve the issue, we need more information in order to help you. What version of Kratos are you using? Is it a SVN repository copy or some release? It would also be helpful if you could post the ProjectParameters file for your model here.

Best Regards,
Jordi

camaosos

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Re: Trillinos FS Kratos Solver stuck
« Reply #2 on: January 03, 2017, 02:27:42 PM »
Dear Jordi,

Thank you for the reply. I changed some parameters (viscosity, density) and it is not getting stuck anymore. The EV OMP_NUM_THREADS was already 1. The solver seems to enter into a deadlock with some parameters.
I'm using Kratos version 5.0.17797 (from repository).

Regards,
Carlos


riccardo

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Re: Trillinos FS Kratos Solver stuck
« Reply #3 on: January 05, 2017, 05:14:15 PM »
Hello,

what solver are u using for the pressure?

are u sure it is a deadlock? maybe it is just doing very many iterations...

Riccardo

camaosos

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Re: Trillinos FS Kratos Solver stuck
« Reply #4 on: January 06, 2017, 05:11:11 PM »
Dear Riccardo,

Thank you for your reply. I'm not sure it is a deadlock, maybe as you say it is a high amount of iterations, the problem is that even with verbosity 2 this case was not printing any error and just got stuck there. I'm using the AMGCL solver for the pressure. I attach the Json parameters file, just changed the extension to txt so I can upload it.

Best regards,
Carlos