# residual oscillation

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 March 13, 2006, 12:36 residual oscillation #1 philippe Guest   Posts: n/a Hello, I am studying enclosed convection in small cavity and I want to evaluate the influence of gas pressure on thermal plume developped by a heated wire at the bottom of the cavity. Under 5 bar results fit well with experience, but for higher pressure, residual values of continuity start to oscillate. Perhaps somebody could help me ? Thank you. Philippe

 March 13, 2006, 14:22 Re: residual oscillation #2 mAx Guest   Posts: n/a switch on unsteady solver

 March 14, 2006, 04:04 Re: residual oscillation #3 philippe Guest   Posts: n/a Ok, but do I use small time step (and it will take a long time) or a large step ? Thank you. Philippe

 March 14, 2006, 04:32 Re: residual oscillation #4 mAx Guest   Posts: n/a if you ust to large time step, it won't converge. you must compute by hand the time step you need. for instance t=(minimum cell size of your domain)/(maximum velocity you are guessing) I would use adaptive time stepping

 March 14, 2006, 04:38 Re: residual oscillation #5 philippe Guest   Posts: n/a I am just trying adaptative time step, thank you very much for your answer. Philippe

 March 14, 2006, 04:40 Re: residual oscillation #6 mAx Guest   Posts: n/a de rien

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