Using an established criterion involving capturing eddies down to the Kolmogorov length scale it can be reasoned that the order of  grid points in the computational mesh needs to be $N^3 \ge Re^{9/4}$ where Re is the Reynolds number of the flow. If $Re \approx 50,000$ then I get about $N^3 \approx 3.7\times 10^{10}$. I know very little about CFD but I am wondering if this is a outrageous requirement given today's high performance computers? I can get access to nodes of a supercomputer cluster. Im not sure of the exact specifications of the cluster, nor which specs are relevant for our purposes of calculating the total time, so if someone could make an assumption and base their calculations on this spec, I could modify my expected computing time once I know what im dealing with.
Expected computational time for DNS computation of fluid flow
fluid dynamics;numerics;performance