what to do when solution doesn't converge?

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 January 27, 2004, 09:30 what to do when solution doesn't converge? #1 Jenny Guest   Posts: n/a Sponsored Links Hi everyone, I'm using SST model. My problem is a steady state fully developed turbulent curved duct flow. Outlet is set as opening with zero pressure and inlet with the velocity profile. The solution seems to stop converging after a certain no. of iteration. Can the separation in flow cause the SST model to fail? http://www.angelfire.com/ab7/cfdwork/RMS.jpg http://www.angelfire.com/ab7/cfdwork/RMS2.jpg http://www.angelfire.com/ab7/cfdwork/RMS3.jpg

 January 27, 2004, 11:31 Re: what to do when solution doesn't converge? #2 Johnson Guest   Posts: n/a Hi Jenny I doubt this is the case. I would suggest looking at your residuals in Post first to see where the maximum values are. I would then examine the resolution of your mesh - very often you may only be able to achieve a certain level of convergence with a certain level of grid refinement. Johnson p.s. do you have re-circulation at your outlet ?

 January 27, 2004, 13:22 Re: what to do when solution doesn't converge? #3 Jan Rusås Guest   Posts: n/a Nice residual curves! Try to define convergence! When I look at your residual curves I would be satisfied, I cant see your problem. Look in your outfile and check the global balances and see if they also are OK. (22 days left as a CFX user

 January 27, 2004, 14:02 Re: what to do when solution doesn't converge? #4 Robin Guest   Posts: n/a Hi Jenny, This doesn't look too bad. You may just be moving through a slow transient, increasing your timestep may help accelerate things. Regards, Robin

 January 27, 2004, 17:52 Re: what to do when solution doesn't converge? #5 Glenn Horrocks Guest   Posts: n/a Hi Jan, 22 days left? Are you moving across to the Dark Side? Glenn

 January 28, 2004, 05:00 Re: what to do when solution doesn't converge? #6 Jan Rusås Guest   Posts: n/a Hi Glenn, I have decided to sacrifice my self for a period and investigate what is going on at the Dark Side (21 days left)

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