Retau Rebulk channelflow
 

Hi,

I have a question to the setup of channel flows comparing with DNS data with Re_tau=395.

To get the bulk velocity I use:

Re_{\tau}=0.073^{0.5} 2^{-5/8} Re_b^{7/8}

to get the bulk velocity of: Re_bulk = 6793.5

Does anyone know, why one rather defines Re_tau than Re_bulk? Is it more correct for comparison or more specific? It probably does not matter, if I am using a Re_bulk of 8000, when taking a look at u+ and y+ anyways!? But then one would calculate and plot u+ and y+ according to the calculated u_tau values, which could be different for each model and mesh!?

Would be nice, if you have some ideas! Flo