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-   -   How many time steps should I use? (http://www.cfd-online.com/Forums/fluent/30052-how-many-time-steps-should-i-use.html)

Dhananjay July 19, 2002 00:09

How many time steps should I use?
 
Hello all,

I am simulating an unsteady, laminar flow in Fluent. I have determined the smallest time scale and am using a time scale which is 1/10th of this as my time step. How do I determine the number of steps that I need though? Is this based on the residence time of the fluid (I have flow in a channel with obstacles in it- so must I take length of channel/velocity as my total time to get an accurate solution?)

Thanks. Dhananjay

Laika July 19, 2002 09:20

Re: How many time steps should I use?
 
--make sure you have good initial conditions (e.g. from a steady calculation)

--choose a time step as such that you have a large residual-drop within each time-step in 20-30 iterations per time-step.

--leave it running

good luck,

Laika, still orbiting


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