# Getting convergence with unsteady problems

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 November 29, 2005, 11:40 Getting convergence with unsteady problems #1 Freeman Guest   Posts: n/a As a rule of a thumb, can I say that when running an unsteady simulation in any turbulence model, when I achieve a periodic oscillation in my residuals and in mass-weighted average plots, etc. solution has converged? If not, this means that mass-weighted average quantities must flatten like in steady simulations? Thanks!

 November 29, 2005, 17:56 Re: Getting convergence with unsteady problems #2 Matt Guest   Posts: n/a Monitor a parameter like Lift or Drag, when they converge then it means your solution has converged. Matt

 November 29, 2005, 18:12 Re: Getting convergence with unsteady problems #3 Freeman Guest   Posts: n/a But in unsteady these parameters I don't think they keep constant: won't they be fluctuating according to also fluctuating velocity and pressure fields?

 November 30, 2005, 11:57 Re: Getting convergence with unsteady problems #4 Matt Guest   Posts: n/a You reach a point where they do not oscillate much hence you can assume that the solution has converged. However, you can still write a PERL script to average out the final results. Matt

 December 1, 2005, 14:13 Re: Getting convergence with unsteady problems #5 Freeman Guest   Posts: n/a OK Matt, many thanks! Then If I've understood well, when I am in unsteady problems I will get the convergence when my parameters of the flow (mass-weighted average and/or drag-coeff, etc.) have a (little) periodic oscillation, doesn't it?

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