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Solution converged, and then diverge again.

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Old   September 11, 2007, 07:01
Default Solution converged, and then diverge again.
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jrg
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Hi. I am simulating a rectangular duct flow with 90 degrees inlet and outlet. Flow is laminar and I use the pressure solver, simpleC, standard pressure and 2nd order upwind momentum discretization.

To assess convergence, I monitor the average velocity at the outlet. After a few hundred iterations (say 300), the value becomes very constant and one would think the solution has converged. But if I keep iterating, oscillations appear and I would need to iterate another few hundred before it becomes constant again. I did in total a few thousand iterations and I could see this cycle repeating.

Does this imply that the solution at 300 iterations is not the converged solution? Is there any possibility that a converged solution would diverge with more iterations?

Thanks.
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Old   September 11, 2007, 15:37
Default Re: Solution converged, and then diverge again.
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AAA
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try adapting velocity gradient
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Old   April 1, 2013, 23:10
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Mohit
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hi .... if u solve this problem then pls send me copy of solution of this.... i am also doing same and facing problem ... my e mail id is mohitmmb@gmail.com



;145276]Hi. I am simulating a rectangular duct flow with 90 degrees inlet and outlet. Flow is laminar and I use the pressure solver, simpleC, standard pressure and 2nd order upwind momentum discretization.

To assess convergence, I monitor the average velocity at the outlet. After a few hundred iterations (say 300), the value becomes very constant and one would think the solution has converged. But if I keep iterating, oscillations appear and I would need to iterate another few hundred before it becomes constant again. I did in total a few thousand iterations and I could see this cycle repeating.

Does this imply that the solution at 300 iterations is not the converged solution? Is there any possibility that a converged solution would diverge with more iterations?

Thanks.[/QUOTE]
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