Hi

I have run a simple pipe flow with periodic boundaries using RANS model. When I checked the velocity in post it was around 0.4 m/s in the middle of pipe. However, according to the paper that I am using, the bulk velocity is 2m/s. Is there a difference between bulk and mean velocity? Thank you

The laminar steady velocity distribution in a circular pipe is parabolic in shape. The mean and bulk velocity are the same thing. It is the average velocity. The max. velocity occurs in the middle of the pipe. Thus the max. velocity appears to be 0.4 m/s (from your statement). The mean velocity is always smaller than the max velocity, thus the mean (bulk) velocity CANNOT be 2 m/s.