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 May 19, 2010, 07:24 Adding centrifugal force #1 Senior Member   Join Date: Nov 2009 Posts: 106 Rep Power: 10 Dear Foamers, I'm running a simulation of a duct using simpleFoam. I would like to add centrifugal force acting on the duct due to its rotation in the model. Is there an easy way to do this in openfoam with my solver? Where could I find information? (checked on the forum but didn't find anything) Thanks for your help

 May 20, 2010, 13:06 #2 Senior Member   Join Date: Nov 2009 Posts: 106 Rep Power: 10 Ok after some research, it seems there are two ways : -MRFSimpleFoam -SimpleSRFFoam SimpleSRFFoam could be suitable but apparently you cannot set the coordinate of the rotation axis ... Does anyone suceeded in makin these solvers working with something else than a propeller, compressor, ... ? In fact I just want my whole geometry to rotate with a certain angular speed...

 May 20, 2010, 16:32 #3 Senior Member   Join Date: Nov 2009 Posts: 106 Rep Power: 10 Here we go for a detailed explanation of my case, what I have, what I want :::::: Geometry : (2D for now but final will be 3D) :::::: http://yfrog.com/09geometryp Very Simple : inlet, outlet, fixedWalls (2D) I've defined my 6 faces as "rotor" since I want all my geometry to rotate :::::: Solver, boundary conditions, ... :::::::: solver : MRFSimpleFoam turbulence model : LaunderSharmaKE RANS Boundary conditions : k Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object k; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0.2646; boundaryField { inlet { type fixedValue; value uniform 0.2646; } outlet { type zeroGradient; } fixedWalls { type fixedValue; value uniform 1e-06; } frontAndBackPlanes { type empty; } } // ************************************************************************* //``` epsilon Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object epsilon; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -3 0 0 0 0]; internalField uniform 4.26; boundaryField { inlet { type fixedValue; value uniform 4.26; } outlet { type zeroGradient; } fixedWalls { type fixedValue; value uniform 1e-06; } frontAndBackPlanes { type empty; } } // ************************************************************************* //``` nut Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object nut; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -1 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type calculated; value uniform 0; } outlet { type calculated; value uniform 0; } fixedWalls { type nutWallFunction; Cmu 0.09; kappa 0.41; E 9.8; value uniform 0; } frontAndBackPlanes { type empty; } } // ************************************************************************* //``` p Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: http://www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { fixedWalls { type zeroGradient; } inlet { type zeroGradient; } outlet { type fixedValue; value uniform 0; } frontAndBackPlanes { type empty; } } // ************************************************************************* //``` U Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: http://www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { fixedWalls { type fixedValue; value uniform (0 0 0); } outlet { type zeroGradient; } inlet { type fixedValue; value nonuniform List 50 ( (0 0.2906 0) (0 0.9366 0) (0 1.7184 0) (0 2.5785 0) (0 3.3476 0) (0 3.9615 0) (0 4.4557 0) (0 4.8674 0) (0 5.2249 0) (0 5.5473 0) (0 5.8476 0) (0 6.1343 0) (0 6.4138 0) (0 6.6906 0) (0 6.9686 0) (0 7.2508 0) (0 7.5400 0) (0 7.8379 0) (0 8.1440 0) (0 8.4518 0) (0 8.7389 0) (0 8.9583 0) (0 9.0807 0) (0 9.1344 0) (0 9.1541 0) (0 9.1541 0) (0 9.1344 0) (0 9.0807 0) (0 8.9583 0) (0 8.7389 0) (0 8.4518 0) (0 8.1440 0) (0 7.8379 0) (0 7.5400 0) (0 7.2508 0) (0 6.9686 0) (0 6.6906 0) (0 6.4138 0) (0 6.1343 0) (0 5.8476 0) (0 5.5473 0) (0 5.2249 0) (0 4.8674 0) (0 4.4557 0) (0 3.9615 0) (0 3.3476 0) (0 2.5785 0) (0 1.7184 0) (0 0.9366 0) (0 0.2906 0) ); } frontAndBackPlanes { type empty; } } // ************************************************************************* //``` As you can see, I start with a profile. In fact these BC are in the same as in my stationnary case since I want everything to be the same EXCEPT that it's rotating with a specified velocity. Now about MRF settings : MRFZones Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: http://www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "constant"; object MRFZones; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 1 ( rotor { // Fixed patches (by default they 'move' with the MRF zone) nonRotatingPatches (); origin origin [0 1 0 0 0 0 0] (0 -0.3 0.0375); axis axis [0 0 0 0 0 0 0] (0 0 1); omega omega [0 0 -1 0 0 0 0] 10; } ) // ************************************************************************* //``` origin is like this because : I want axis of rotation to @center on Z and X and below my duct (y position) Axis of rotation is Z I set low speed to be "easy" on beginning. I've done nothing else. Mesh was generated with gambit with, like I said, fluid zone set as "rotor" and exported via fluentMeshToFoam -writeSets -writeZones. Now when I make MRFSimpleFoam, it's working but solutions are very weird. See velocity field and pressure field : pressure : http://yfrog.com/14pfieldp velocity : http://yfrog.com/6luyfieldp vector field : http://yfrog.com/j1vectorrp What do you think? To me solution is weird ... but vector field seems to take rotation into account... But inlet BC seems not since vecor field near the inlet is shifted to the left since the beginning of the duct... Could you please help me? Where am I wrong? Thank you for the help Convergence for Ux,Uy,p is OK (10^-6) but k and epsilon say @10^-3 Last edited by Gearb0x; May 20, 2010 at 16:37. Reason: wrong word

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