Turbulence Modification Due to Inertial Particles in a Rough-Wall Pipe

Abstract

Particle-laden turbulent flows are both technologically important and challenging to understand. This is especially true in rough-walls as opposed to smooth-wall flows, and when the particle loading becomes higher such that particles affect the turbulence-the two-way coupling regime. Depending on the Stokes number and particle volume fraction, turbulence can be suppressed or enhanced by the particles. Direct numerical simulations with the point particles were conducted in order to better understand the particle turbulence interaction. At low volume fractions, the mean force of the particles relative to the driving force of the flow is low and does not affect the turbulent flow. At higher volume fractions, particles with large Stokes number collide frequently with the rough walls behaving like a sink. Particles with smaller Stokes number have a more complicated interaction with the flow turbulence, where we observe both suppression and reappearance of turbulence over long time scales causing the mean flow to pulsate.

Evaluation of RANS-DEM and LES-DEM Methods in OpenFOAM for Simulation of Particle-Laden Turbulent Flows

“…DNS-DEM studies [6,7] are limited to simple flows, a small number of particles, and mainly to the PP approach due to heavy computational requirements. DNS performed on PP in rough-wall pipe with a small Reynold's number indicates that particle volume fraction (α p ) and Stokes number (St) play an important role in turbulent modification [8]. Recently, a two-way coupled DNS study on particle-laden flow highlighted the effects of the particle Stokes number (St) on near-wall turbulence [9].…”