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 March 11, 2011, 09:08 Numerical schemes for free surface flows (VOF) #1 New Member   Bo Terp Paulsen Join Date: Oct 2010 Posts: 13 Rep Power: 8 Dear all, I am currently working with free surface flows using the interFoam solver. Unfortunately I have some serious problems with violent instabilities in the air phase and wondered however this is related to the numerical schemes? An Example of the instabilities are shown in this figure. In the figure the velocity field is shown with a contour of the VOF-scalar (gamma=0.5) superimposed. As seen from the figure, vortices are created in the air and the free surface surface is highly distorted. The distortion of the free surface is non-physical and ruin the computations. So, if anyone has experience with the numerical schemes in relation to the interFoam solver and/or the VOF scheme in general, I will appreciate some advice! Currently I am using the settings from the damBreak tutorial. Kind regards, Bo Terp ascotdreamer likes this. Last edited by botp; March 11, 2011 at 10:57. Reason: Additional information added

 March 11, 2011, 12:28 #2 Senior Member     Santiago Marquez Damian Join Date: Aug 2009 Location: Santa Fe, Santa Fe, Argentina Posts: 436 Rep Power: 17 Hi Bo Terp, I had same problems solving an sloshing case. I've been solving other cases too and my suggestion would be run with this parameters: -upwind difference scheme for all div terms. -5 PISO correctors -nAlphaCorr no more than 1 -nAlphaSubCycles, no more than 1 -cAlpha=0 -Courant number below or equal to 0.2 (use adjustTimeStep to do that) once you have a very diffusive but bounded solution both in alpha and U, then try increasing cAlpha and changing the div schemes to which are used in interFoam tutorials. Let me know of your findings, I'm learning too. Regards shipman likes this. __________________ Santiago MÁRQUEZ DAMIÁN, Ph.D. Research Scientist Research Center for Computational Methods (CIMEC) - CONICET/UNL Tel: 54-342-4511594 Int. 7032 Colectora Ruta Nac. 168 / Paraje El Pozo (3000) Santa Fe - Argentina. http://www.cimec.org.ar

 March 11, 2011, 16:27 #3 Senior Member   Claus Meister Join Date: Aug 2009 Location: Wiesbaden, Germany Posts: 241 Rep Power: 11 Properly you have an unstructured mesh which contains non-orthogonal cells. Can you post the current one? I don't know the exact boundary conditions but I would suggest you set something like PISO: nCorrectors 2; nOrthoCorrectors 4; Schemes: div(rho*phi,U) Gauss limitedLinearV 1; div(phi,alpha) Gauss vanLeer; div(phirb,alpha) Gauss interfaceCompression 1; Alternatively, I can recommend div(phi,alpha) Gauss limitedLinear 1; div(phi,alpha) Gauss linearUpwind cellMDLimited Gauss linear 1; Setting cAlpha 0 means no interface compression, take cAlpha 1. Hasn't that work than increase to 2,3,4 etc. Cheers tikulju likes this. Last edited by idrama; March 12, 2011 at 03:17.

 Tags numerical scheme, openfoam 1.5-dev, vof model

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