Transport of particles in a turbulent rough-wall pipe flow

Abstract

Dense, small particles suspended in turbulent smooth-wall flow are known to migrate towards the wall. It is, however, not clear if the particle migration continues in a rough-wall flow and what the responsible mechanism is, especially with changing roughness parameters. Here, we address this using direct numerical simulation of a turbulent pipe flow of a fixed friction Reynolds numbers and changing the roughness size as well as the Stokes number of the particles. The transport and deposition mechanisms of particles are segregated into three different regimes dictated by the Stokes number. Particles with small Stokes number follow the carrier fluid and are affected by the turbulent structures..