# solution diverges when linear upwind interpolation scheme is used

 Register Blogs Members List Search Today's Posts Mark Forums Read May 29, 2010, 01:23 solution diverges when linear upwind interpolation scheme is used #1 New Member   subash Join Date: Feb 2010 Posts: 10 Rep Power: 15 Hi, I am trying to simulate supersonic flow over a ramp. The solution works well when I use a limitedlinear 1 interpolation scheme for div, but when it is converted to a second order interpolation scheme(linear upwind) the courant number which floats around 0.45 for quite sometime seems to jump suddenly to values above thousand with the number of inner iterations reaching 1000's. I have tried to run it with constant courant number also but still the solution diverges. the fvScheme file which works fine is as shown below ddtSchemes { default Euler; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) Gauss limitedLinearV 1; div(phi,k) Gauss upwind; div(phi,epsilon) Gauss upwind; div(phi,R) Gauss upwind; div(R) Gauss linear; div(phid,p) Gauss limitedLinear 1; div(phiU,p) Gauss limitedLinear 1; div(phi,h) Gauss limitedLinear 1; div((muEff*dev2(grad(U).T()))) Gauss linear; } laplacianSchemes { default none; laplacian(muEff,U) Gauss linear corrected; laplacian(DkEff,k) Gauss linear corrected; laplacian(DREff,R) Gauss linear corrected; laplacian(DepsilonEff,epsilon) Gauss linear corrected; laplacian((rho*(1|A(U))),p) Gauss linear corrected; laplacian(alphaEff,h) Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default yes; p; } And the modified file which is diverging is as follows ddtSchemes { default Euler; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) Gauss linearUpwind Gauss; div(phi,k) Gauss linearUpwind Gauss; div(phi,epsilon) Gauss linearUpwind Gauss; div(phi,R) Gauss linearUpwind Gauss; div(R) Gauss linear; div(phid,p) Gauss limitedLinear 1; div(phiU,p) Gauss limitedLinear 1; div(phi,e) Gauss limitedLinear 1; div((muEff*dev2(grad(U).T()))) Gauss linear; } laplacianSchemes { default none; laplacian(muEff,U) Gauss linear corrected; laplacian(DkEff,k) Gauss linear corrected; laplacian(DREff,R) Gauss linear corrected; laplacian(DepsilonEff,epsilon) Gauss linear corrected; laplacian((rho*(1|A(U))),p) Gauss linear corrected; laplacian(alphaEff,e) Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default yes; p; } can someone please tell me how do I recognise(in OpenFoam) whether a transient problem being run is explicit or implicit. Also how do I get the problem to converge with second order upwind scheme. Thank you.  Thread Tools Search this Thread Show Printable Version Email this Page Search this Thread: Advanced Search Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules Similar Threads Thread Thread Starter Forum Replies Last Post rassilon OpenFOAM Running, Solving & CFD 0 April 8, 2010 02:51 titio OpenFOAM Running, Solving & CFD 0 October 12, 2009 11:03 waynezw0618 OpenFOAM Running, Solving & CFD 39 March 5, 2009 12:57 KM CFX 4 September 27, 2007 14:41 Biga FLUENT 0 January 12, 2006 12:41