Number of elements x double precision
 

I'm running a simulation of wind tunnel and have a question related to the number of elements and double precision. On the computer that I'm running it's possible to run (without double precision) a mesh with 3 million elements (maximum). I'm worried about the results (because of single precision) so I decreased the mesh to 1.5 million to run it with double precision. It's always good to perform a simulation with high number of elements? Double precision is always important or it's better to use a higher mesh and run with single precision?

Thanks!

Details please...
 

What is your solver? Mesher? Application?

thx
 

Sorry:

Solver: ANSYS CFX Solver
Mesher: ANSYS (Advanced meshing)
Application: I'm need to validate experimental results (academic purposes).