# div and laplacian

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 November 22, 2013, 10:18 div and laplacian #1 Member   Reza Join Date: Feb 2012 Posts: 67 Rep Power: 6 Hi friends, I want to generate some equations in open foam. My interest is to generate (d2v/dx2)+(d2v/dy2). But in openfoam there is "div" and "laplacian" commands which make equations in x, y and z directions and I want just in x and y directions. What can I do? Thank you in advance for your help and comments. Kind Regards

 November 22, 2013, 10:32 #2 Senior Member   Bernhard Join Date: Sep 2009 Location: Delft Posts: 790 Rep Power: 14 Use a 2D mesh, i.e. flat and parallel front and back planes, with only one cell. Set the boundary conditions to empty. gooya_kabir likes this.

November 22, 2013, 10:40
#3
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Reza
Join Date: Feb 2012
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Quote:
 Originally Posted by Bernhard Use a 2D mesh, i.e. flat and parallel front and back planes, with only one cell. Set the boundary conditions to empty.
thanks for your response . But my geometry is 3D, and just I want to apply an equation which has gradient in x and y directions.?!

 November 23, 2013, 08:12 #4 Senior Member   Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Deltares, Delft, The Netherlands Posts: 1,702 Rep Power: 27 Hallo, This basically means that you are solving a system in 3D, which is of the form: I believe that the Laplacian operator in OpenFoam does support a diffusivity as a tensor of rank two, which basically means that the above equation could be re-written as: where and . Good luck, Niels gooya_kabir likes this. __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.

November 25, 2013, 05:28
#5
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Reza
Join Date: Feb 2012
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thank you. I think I could not transform my words. I want to apply the below equation, what's the mathematical description of this equation in open foam?

-∂p/∂x=μ((∂^2 v)/(∂y^2 )+(∂^2 v)/(∂z^2 ))

Quote:
 Originally Posted by ngj Hallo, This basically means that you are solving a system in 3D, which is of the form: I believe that the Laplacian operator in OpenFoam does support a diffusivity as a tensor of rank two, which basically means that the above equation could be re-written as: where and . Good luck, Niels

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