Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
time discrete solver
Posted 26 ago 2011, 05:38 GMT-4 Fluid & Heat, Computational Fluid Dynamics (CFD), Studies & Solvers Version 4.2, Version 4.3 1 Reply
Please login with a confirmed email address before reporting spam
what do you say about the time discrete solver? I use transient flow for switching on buoyancy force in a buoyancy driven flow field.
Using the BDF solver the model runs but it needs much computation time for iteration of the nonlinear couplings (mass and heat transfer -> T,c -> rho -> Fz -> flow). I have looked for a possibility to use Fz from the previous timestep for a long time.
Now I f found the COMSOL operator prev(expr,i) what evaluate prev(c,1) concentration from the previous time step f.i. The operator prev works with the time discrete solver only.
I use the orperator to calculate Fz based on results of the pervious time step. The model runs fast with a larger timestep compared with the BDF method. What are your experiences? How can I control the timestep?
Best regard
Michael
Hello Michael Rembe
Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.
If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.
Please login with a confirmed email address before reporting spam
I noticed that you can control the time-step in solver node (time discrete solver node). By default it is set to be 0.01. I am still working with it. This solver is slower compare to time dependent solver, and it is harder to get convergence out of it for multiphase flow modeling.
If you have found any thing with it please share.
--
Shawn