CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Convergence in multiphase flow !! HELP !!! (http://www.cfd-online.com/Forums/fluent/30341-convergence-multiphase-flow-help.html)

lohen September 26, 2002 04:47

Convergence in multiphase flow !! HELP !!!
 
Hi, i'm making gas-liquid flow simulations. I began with time step equal to 1e-06 s, otherwise convergence is impossible. it began then to converge, and i can fix time =1e-04s, but after a few time step, convergence is more and more difficult to reach and I have to lower the time step size. Can somebody explain me why ?????

Thanx

Atholl September 26, 2002 10:10

Re: Convergence in multiphase flow !! HELP !!!
 
Try increasing the time step by smaller increments!

lohen September 27, 2002 03:43

Re: Convergence in multiphase flow !! HELP !!!
 
yes I did that, but when I get from 1e-06 to 1e-05, it takes 10 to 5 iteration per time step to converge. So I get to 1e-04, then it convergences. And after a few time steps, convergence stops. And time step size wants to be lowered. Thanx though !!!

Newbie September 27, 2002 16:27

Re: Convergence in multiphase flow !! HELP !!!
 
try smaller underrelaxation parameters.

newbie

Pravesh Kumar October 3, 2002 11:28

Re: Convergence in multiphase flow !! HELP !!!
 
Hi you can use adaptive time stepping method in place of fixed.


All times are GMT -4. The time now is 06:45.