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-   -   guidelines on time step (http://www.cfd-online.com/Forums/fluent/32960-guidelines-time-step.html)

Effendi Ali February 3, 2004 21:36

guidelines on time step
 
hi all, to be straight to the point, my simulation is about boiling. i have problem on deciding the correct time step, since different time step will vary the simulation result (although on the same flow time)

example: 1 time step of 1s 10 time step of 0.1s 100 time step of 0.01s and 1000 time step of 0.001s all of it will generate different result

please enlighten me

thanks you in advance

mateus February 4, 2004 03:41

Re: guidelines on time step
 
Hi!

Do all simulations converge? In principle the right time step should be about 100 times smaller then the (1/igenfrequency) of the phenomenon. At least that's my experience... Check out the courant number also..

regards

MATEUS

prasanth February 4, 2004 07:15

Re: guidelines on time step
 
hai Ali and mateus, I am also facing the same problem. mateus, yeah for some time steps it will converge. some cases wont. according to you, how to calculate courant number for two-phase problem? I kknow general formula for courant number.'

thnks and rgds prasanth

Effendi Ali February 4, 2004 08:50

Re: guidelines on time step
 
thanx for your response mateus and prasanth

yes it is converge for every single time step (i make sure there are enough iterations per time step)



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