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hugocis June 1, 2010 04:40

unsteady divergence simple case
 
im curently workin on a cylindrical obstacle in a pipe... i hav some convergence issues...my calculation is unsteady.
i really need help, regards

valgrinda June 9, 2010 08:21

Timestep control
 
Hei,

possibly your time step is too large. Especially if you use explicit time treatment or implicit time stepping without under relaxation, high CFL numbers (CFL>1) cause numerical instability.
In case you use your own program and have access to the source code, consider adaptive timestep control.

Regards
Hans

hugocis June 10, 2010 04:24

my parameters are fine. i changed the URF's and it is workin but i had to increase the inner iterations...at least it is converging even if itll be longer
by the way im using implicit scheme with URF's


regards, Francis


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