topic Re: Local mesh size for Grid Convergence Index in CFD Forum

Local mesh size for Grid Convergence Index

OmkarJ — Thu, 28 Feb 2013 15:55:51 GMT

Hello,

I am trying to streamline the mesh independence practices using Grid Convergence Index and Richardson Extrapolation as they are considered the best in practical CFD. (Ref: Roache, P. J. "Perspective: a method for uniform reporting of grid refinement studies." TRANSACTIONS-AMERICAN SOCIETY OF MECHANICAL ENGINEERS JOURNAL OF FLUIDS ENGINEERING 116 (1994): 405-405.)

Now, element sizes for the consecutive meshes should be known to get the grid refinement ratio used in the calculations in this procedure. But unfortunately, we use unstructured mesh along with the extruded mesh so it is not possible to do the manual meshing and we are relegated to the automatic method. Is it possible to get a local size of the mesh obtained by automatic method in SimCFD?

If not, then can anyone suggest how I go about estimating this ratio based on the values of element-count of two meshes?

Thanks

Omkar

Re: Local mesh size for Grid Convergence Index

OmkarJ — Tue, 05 Mar 2013 08:41:23 GMT

Anyone?

Re: Local mesh size for Grid Convergence Index

Anonymous — Tue, 05 Mar 2013 13:22:18 GMT

try to use a refinement region with the option "equal mesh sizes". Then you can enter the mesh size value in the geometry unit.

Re: Local mesh size for Grid Convergence Index

OmkarJ — Tue, 05 Mar 2013 14:58:34 GMT

Thanks, but I found out a simple empirical formula Roache suggested to calculate the refinement ratio based on no. of elements, which is (N1/N2)^(1/D).

where N1 and N2 being the elements of two meshes and (N1/N2) and D is the dimensionality of the problem.

Cheers