Abstract
Direct Numerical Simulation (DNS) has been performed for a turbulent flow in a channel with rough and smooth walls. The Navier-Stokes equation and the equation of continuity for Reynolds number Re_m=4560 have been solved numerically with the finite difference method. As a result, it is found that the values of shear stress and pressure fluctuation increase markedly as the flow goes downstream because of the influence of rough wall. Also it is confirmed that longitudinal vortices are enhanced by the influence of rough wall.
