[Ardalan]

Which components of velocity are used by fluent and cfx?
curvilinear (covariant) or cartesian?
Which one is more preferable?
For an external turbulent flow over a blunt body which one do u suggest?

[mprinkey]

Originally Posted by Ardalan

Which components of velocity are used by fluent and cfx?
curvilinear (covariant) or cartesian?
Which one is more preferable?
For an external turbulent flow over a blunt body which one do u suggest?

I don't know anything about CFX, but Fluent, in a sense, uses both. The momentum components are formulated in normal cartesian frame. I suspect the same to be true for all unstructured codes...only meshes that are mapped really have a uniquely defined covariant frame. Having said that, Fluent (and OpenFOAM) defines its mass fluxes as scalar values oriented normal to the boundary faces. In a sense, these fluxes are covariant.

I can't really answer your question about which is preferable. If you have a finite difference solver and an analytical mapping for the grid, the covariant frame may give you slightly better precision in resolving flows near the surface, as the surface-normal component will be small or zero and the tangent components may be orders of magnitude larger. In 64-bit floating point, I doubt that will make much of a difference though.