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-   -   benefits of c-meshing ? (http://www.cfd-online.com/Forums/main/108522-benefits-c-meshing.html)

Umuteng October 25, 2012 09:46

benefits of c-meshing ?
 
Hello everyone,

For 2-d flow over airfoil analysis what is the advantage of c-meshed domain over the unstructured meshing options?

Best regards...

cdegroot October 26, 2012 12:28

Using quadrilateral elements rather than triangular elements is more accurate when using finite volume methods. I'm not sure how much you know about the disretization details, but if you take a line that connects the centroid of two adjacent volumes it does not in general pass through the integration point on the cell face and you will have to apply corrections to get to the right point. If the grid is orthogonal this line passes directly through the integration point, so no correction necessary. The more closely orthogonal the mesh, the smaller this correction will be and the more accurate your results will be (in general).

Also, triangular/tetrahedral meshes don't do as good of a job of resolving boundary layers as quad/hex meshes since the grid lines are in not aligned with the flow.

Ford Prefect October 29, 2012 08:36

Probably the ease of mesh generation (if you have a more complex geometry), and number of generated cells?

However, you still need to apply a correction in structured body-fitted meshing since you need to calculate a Jacobian. How this affects accuracy compared to the unstructured form of correction should be interesting to know.

I agree on the boundary layer treatment, it poses some additional problems if you use triangular elements in that region.

Umuteng October 31, 2012 17:51

thank you guys, however i think i need more detailed information so could you advice any papers which is related to this phenomena ?

vicarious October 31, 2012 19:06

Because of the accuracy needed for flow prediction close to the walls, specially for an airfoil with high pressure gradients, It is more common to use and structured mesh around these complex geometries. You can produce an uniform cells down to walls and control the Y+ much easier. It also saves time and memory more than unstructured grids. Briefly, boundary layer resolving is much more accurate. Maybe you find the attachment below useful.
http://www.4shared.com/office/an7yoH...rid_Types.html

Umuteng October 31, 2012 19:27

thank you very much for informations, and document you share...


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