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-   -   creating 2D model with solidworks (http://www.cfd-online.com/Forums/cfx/115835-creating-2d-model-solidworks.html)

 Magma April 8, 2013 05:46

creating 2D model with solidworks

Dear All,
I have been trying to work with 2D model imported from Solidworks. Seems like the model becomes 3d. How much thickness of model would be good. Generally it is recommended 1 cell thickness? How much is that exactly?

 oj.bulmer April 8, 2013 07:18

The CFX only works with 3D geometries and hence a 2D geometry will be converted into 3D one. The same would happen to CFD-Post, wherein a 2D mesh from Fluent will be seen as a 3D.

How much thick? - One cell thick! The exact value of thickness will be decided by your overall geometry but the term "once cell thick" comes from how symmetry BCs treat this. Try a thickness that you think is small enough and mesh it. But make sure that the number of cells in the thickness direction is one! Since you will apply symmetry at both the big bounding surfaces, they ensure there is no gradient within this one cell distance throughout the domain. As long as your thickness is small enough, mesh is good, solution converged and no. of cells in thickness direction is one, it won't matter what the exact value should be.

As a thumb rule, you can have a look at a cell size of left-bottom most corner, and see is the cell size is approximately comparable. Though, it shouldn't matter as much.

OJ

 ghorrocks April 8, 2013 08:18

A minor oversight - the recommended thickness of a 2D simulation in CFX is the length of the smallest element. This reduces meshing round off errors. This is discussed int he FAQ: http://www.cfd-online.com/Wiki/Ansys...tion_in_CFX.3F

 Magma April 8, 2013 23:35

Cell thickness

Thanks to both of you!!

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