Solution converged, and then diverge again.
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. 
Re: Solution converged, and then diverge again.
try adapting velocity gradient

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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