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September 3, 2009, 06:00 |
SimpleFoam Boundary Conditions
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#1 |
New Member
Join Date: Sep 2009
Posts: 1
Rep Power: 0 |
Hi
I have a question about the boundary conditions in simpleFoam. I want to modify the pitzDaily Tutorial with other boundary conditions. I want a static low pressure at the outlet. My p file looks like this: /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.5 | | \\ / 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 { inlet { type zeroGradient; } outlet { type fixedValue; value uniform -5000; } upperWall { type zeroGradient; } lowerWall { type zeroGradient; } frontAndBack { type empty; } } // ************************************************** *********************** // And I donīt want to have a fixed magnitude. My solution would be a velocity profile. My U file looks like this: /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.5 | | \\ / 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 { inlet { type zeroGradient; } outlet { type zeroGradient; } upperWall { type fixedValue; value uniform (0 0 0); } lowerWall { type fixedValue; value uniform (0 0 0); } frontAndBack { type empty; } } // ************************************************** *********************** // The Problem is that I have not a right solution. I think the U file is not correct. Thanks for your help Johannes |
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September 4, 2009, 04:22 |
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#2 |
Senior Member
Join Date: Apr 2009
Location: Karlsruhe, Germany
Posts: 103
Rep Power: 17 |
Hi,
simpleFoam solves incompressible. For this kind of simulation normally you set for the inlet condition: pressure: zerogradient velocity: fixedValues (Ux Uy Uz) and for outlet condition: pressure: fixedValue velocity: zeroGradient Regards Thomas |
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September 4, 2009, 07:38 |
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#3 |
New Member
Oscar
Join Date: Jun 2009
Location: Murcia, Spain
Posts: 14
Rep Power: 16 |
I wouldn't use zeroGradient for both velocity and pressure at the inlet... one of them should have a value. If not, the problem is not well described.
By the way, do you really need to use negative pressures? |
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September 7, 2009, 17:29 |
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#4 |
Senior Member
Steve Hansel
Join Date: Jun 2009
Location: Colorado, USA
Posts: 112
Rep Power: 16 |
You haven't set enough conditions. The problem as you described it could simply be solved by making the pressure -5000 everywhere and having no flow. Or it could pick just about any flow and calculate the pressure to meet it.
You need to define a pressure or velocity somewhere else, probably the inlet. |
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