On Tue, Jun 28, 2011 at 8:03 AM, Saumil Patel <[email protected]> wrote: > Thank You, John. This makes sense. I was able to get results for Re 100. > > I have been trying to get results for Re = 1000. I've tried two approaches: > 1) to multiply the diffusion term by 1/Re and 2) Change the boundary > condition to U=1000. BC's are still based on the Penalty formulation. > > In both cases I'm using a refined mesh of 500 by 500. > > I'm having trouble getting accurate results so I was wondering if the > K-matrix is becoming ill-conditioned when I multiply the diffusion term by > .001 (1/Re)? Do you have any suggestions on getting around it this issue?
The matrix condition number goes like h^-2 for the Laplacian, so the fine mesh will certainly hurt you there. The cell Reynolds number, Re*(h/L) = 1000/500 = 2 for your case, which is right on the borderline of Galerkin instability. The timestep, linear, and nonlinear tolerances will all need to be different from what they were in the Re=1 case. You'll need to play with those and see which ones work. -- John ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
