# Error due to Unstructured Mesh with custom solver

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 February 22, 2013, 08:11 Error due to Unstructured Mesh with custom solver #1 Senior Member   HECKMANN Frédéric Join Date: Jul 2010 Posts: 237 Rep Power: 10 Edit, problem solved Dear all, I'm facing some issues with unstructured Mesh (quality is ok and Skewness is less than 0.45) with my custom solver. My "density variable" has some strange error lines that follows the flow streamlines as shown bellow. The picture shows the normalized density (1 is the freestream value) when the case reaches steadyness. I tried different scheme, the linearUpwindV scheme improve/smooth a little the results but it's not perfect yet. My case computes the behavior of highly dispersed particles in a fluid (only the fluid impact the particles motion through the drag) using an Eulerian approach. The goal is to compute the particles collection over a cylinder (some particles impact the cylinder and some are moved away by the air flow via drag) My solver: An unsteady Eulerian solver to compute the behavior of highly dispersed tiny particles in a fluid (only the fluid impact the particles motion through the drag). Nomenclature : - volume fraction of the particles - velocity of the particles - function of the relative Reynolds number - time respond of the particle - velocity of the fluid Continuity equation : Momentum equation My scheme Code: ddtSchemes { default backward; } divSchemes { default no; div(phiR,U) Gauss linearUpwind grad(U); div(phi,rho) Gauss upwind grad(rho); } gradSchemes { default Gauss linear; } laplacianSchemes { default Gauss linear; } interpolationSchemes { default linear; } snGradSchemes { default fourth; } fluxRequired { default no; rho ; } EDIT: I've found a solution To solve my problem, I used a skewCorrected My new fvSchemes is: Code: ddtSchemes { default backward; } divSchemes { default no; div(phiR,U) Gauss skewCorrected linearUpwind grad(U); div(phi,rho) Gauss skewCorrected upwind grad(rho); } gradSchemes { default Gauss linear; } laplacianSchemes { default Gauss linear; } interpolationSchemes { default linear; } snGradSchemes { default fourth; } fluxRequired { default no; rho ; } chegdan, wyldckat, Pat84 and 3 others like this. Last edited by fredo490; February 24, 2013 at 08:22. Reason: problem solved

 February 23, 2013, 04:04 #2 Senior Member   HECKMANN Frédéric Join Date: Jul 2010 Posts: 237 Rep Power: 10 I've checked my problem with a structured grid having the same y+ and the small disturbances are gone... The problem is linked to the unstructured but I cannot find any scheme able to smooth/correct those errors.

 March 6, 2015, 03:46 #3 Senior Member   Dongyue Li Join Date: Jun 2012 Location: Torino, Italy Posts: 756 Rep Power: 10 Hello HECKMANN! Could u pls upload a comparison of contour plot of the right result? Using skewCorrected scheme. Thanks.

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