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Jennifer Haque July 16, 2004 16:49

Dear All,

I am running a transient simulation and the convergence after the first 14 timesteps, seems to be fluctuating quite a lot. Is is normal to see quite a lot of fluctuations at the beginning of a transient run? Any comments or advice on how to improve this would be much appreciated.

Kind Regards Jennifer

Anne July 17, 2004 06:12

Re: transient
Hi Jennipher,

What are your time steps and coefficient loops? Have you tried reducing them?

In principle, such oscilation can be resolved by either increasing the coefficient loops or reducing the time step. CFX people recommend the latter, and from experience, I agree.

regards, Anne

Glenn Horrocks July 18, 2004 18:41

Re: transient
Hi Anne, Jennifer,

Often the initial conditions mean that there is some rapid transients occuring in the first few timesteps until it all settles down and the flow properly establishes itself. This means yes, it is common to have the solution fluctuate rapidly in the early part of the simulation until it settles down.


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