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 gooya_kabir November 22, 2013 10:18

div and laplacian

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?

Kind Regards

 Bernhard November 22, 2013 10:32

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 November 22, 2013 10:40

Quote:
 Originally Posted by Bernhard (Post 463092) 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.?!

 ngj November 23, 2013 08:12

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 November 25, 2013 05:28

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 (Post 463190) 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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