Rough Wall-Bounded Turbulence Over Unsteady Channel Flow Using Direct Numerical Simulations

Direct Numerical Simulations of unsteady channel flow has been performed over a regular rough surface. Flow has been initiated by applying an unsteady nonzero mean forcing in the form of a time-varying pressure gradient. The simulation of two different Reτ of 180 and 395 was performed and compared. Our aim is to investigate the difference in turbulence statistics of the smooth side with the rough side such as mean statistics, phase averaging of the unsteady channel wall. Further extending the findings of the streaks response for both the Reynolds number on the rough turbulent surface vicinity. The current simulation indicates the difference in a structure near the wall as the Reynolds number increase. Flow visualization has demonstrated differences due to roughness for the Reτ of 395 compared to Reτ of 180.