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sisir August 17, 2008 09:49

Reynolds number
Dear All,

How to get "Reynolds" numer from the "Cell Reynolds Number" of the computational domain. pls help me.

Thanx; sisir

Jason B August 18, 2008 12:43

Re: Reynolds number
You can't. Cell Reynold's Number is relative to the individual cell (Re_cell = rho_cell * v_cell * Vol_cell^0.333 / Mu_cell) and does not contain information about the geometry, just the local cell volume and flow values. Depending on the discretization scheme used and the mesh coarseness, the Re_cell can be used to imply model stability.

The Reynold's number of your geometry is something you define. If you're comparing to past results, use the same definition for Reynold's number that they used. i.e. for a finite cylinder, did they use the length, or the diameter (diameter is typical, I just picked a geometry with two simple dimensions to use as an exmaple)? Rho, V, and Mu are typically "free stream" quantities and can (most likely) be calculated at your inlet boundary condition depending on your model.

Reynold's number is too much of an "arbitrary" concept to have it built into the CFD, therefore its something you have to calculate.

Hope this helps, Jason

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