Hello,
I have a CS 8.03 / Syrthes 5.0 coupled thermal problem. The coupled solution is very slow.
-About 300k cells
-The solid problem solves in ~10 seconds in Syrthes, 1 core
-The fluid problem solves in ~60 seconds in CS, 1 core
-The coupled problem, CS - Syrthes will not stabilize, after even 3+ hours (1 core, or 4 cores/4 cores) The coupling for thermal is very slow to converge. It slowly settles towards what I think is the solution
Per the tutorial, it appears that time stepping must be fixed, not adaptive. If I increase the time step, the fluid solution will diverge.
Changing CDTVAR from 1 to 10 does not change anything, I thought this was to speed up the T solution vs the fluid solver. I do not see other relaxation / or controls to speed this thermal solution up. There are options for specifying solvers for T. Any guidance for this issue?
files attached. The interface will not allow me to attach a .syd
Thank you
Coupling, very slow temperature convergence
Coupling, very slow temperature convergence
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Re: Coupling, very slow temperature convergence
Hello,
If this should converge to a steady-state solution, the time steps do not need to be identical between the fluid and solid domains. In this case, I would recommend the pseudo-steady algorithm on the code_saturne side (with a local time step), as this will optimize for the CFL number and usually provide a good compromise between stability and speed of convergence.
Best regards,
Yvan
If this should converge to a steady-state solution, the time steps do not need to be identical between the fluid and solid domains. In this case, I would recommend the pseudo-steady algorithm on the code_saturne side (with a local time step), as this will optimize for the CFL number and usually provide a good compromise between stability and speed of convergence.
Best regards,
Yvan
Re: Coupling, very slow temperature convergence
Great, thank you. I will try that.
From your comments, it sounds like the total steps and step size need to be the same only for transient problems.
Much appreciated.
From your comments, it sounds like the total steps and step size need to be the same only for transient problems.
Much appreciated.