Posted Mon, 25 Jun 2007 17:39:55 GMT by amelia
My Steady State Model has a high mass balance error (7%) however a long term transient run of the same model with no changes to stresses has a low mass balance error (0.1%).  I am trying to resolve why the Pseudo Steady State model has such different mass balance error.  I am using the deformable mesh surface definition (top layer free and movable).  Are there problems with trying to reproduce the same results with a steady state and a pseudo steady state when using the deformable mesh?  Moreover, is the Pseudo Steady State Mass Balance error more representative or less representative of the models computational accuracy than the SS mass balance error? 
Posted Mon, 02 Jul 2007 14:54:37 GMT by Boris Lyssenko
In general there are no problems with mass balance errors in models with deformable mesh. If you run a steady-state model, however, convergence is much more difficult to achieve then in running the same model in quasi-steady state. For extremely complex models, it might even be the only chance to run them in transient mode. In cases where you observe high mass balance errors in steady state, you should try to improve model stability by the usual means like setting initial conditions closer to the results, refining the mesh in high-gradient zones, reducing the parameter contrasts, etc.

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