Numerical investigation of secondary flows in a turbulent pipe flow with sinusoidal roughness

Abstract

© 2018 Australasian Fluid Mechanics Society. All rights reserved. Recent research on turbulent flow over heterogeneous rough walls have reported the occurrence of secondary motions which extend to the edge of the boundary layer. In this study, direct numerical simulations (DNSs) of turbulent flow in a rough-wall pipe are conducted where the pipe surface consists of a three-dimensional sinusoidal surface. The roughness semi-amplitude height (h+) is fixed at 60 viscous units while the wavelength of the roughness elements is varied to investigate the effects of solidity or effective slope (ES). The rough-wall cases, which vary from the wavy regime (ES = 0.18 with a viscous roughness wavelength,..