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 Jade M March 11, 2010 17:16

Conformal Mesh

I am new to finite element modelling of fluid dynamics and heat transfer. What is the definition of a conformal mesh? Why does it matter? When and why is it better to have a conformal mesh?

Thanks so much for any greatly needed help! :)

 jchawner March 13, 2010 17:37

Let's start from the basics. If your mesh isn't conformal, it's non-conformal. By conformal, we mean that the cell boundaries conform to the shape of the boundary you're trying to simulate. A non-conformal mesh, therefore, does not conform to the boundary shape.

As an example of a non conformal mesh, image you're simulating flow over an airfoil and your grid is a cartesian mesh like a sheet of graph paper with only constant x and constant y grid lines. If you zoom in on the airfoil, you'll see that the airfoil shape cuts through some of the cells in your grid. Your solver has to account for that somehow. One way is to "stairstep" the grid by eliminating cells inside or cut by the boundary. The resulting mesh is highly irregular, leaving a jagged hole where the airfoil was. A second way is to compute how the airfoil cuts each cell leaving behind only a fraction of a square (in my graph paper analogy). Then your solver has to account for cells that are polygons.

So a non-conformal grid introduces accuracy problems due to resolving the boundary shape and complexity issues in the solver.