Particle deposition in circular pipes with variable bed height

Abstract

Reynolds-averaged Navier-Stokes modelling of particle-laden turbulent flows is studied for circular pipes with simulated bed heights of 0, 0.25 and 0.5 of the pipe diameter. A Lagrangian particle tracking technique is used to predict the deposition of spherical particles with sizes ranging from 5-500 μm. Secondary flows are observed to be present in the circular pipe flows with bed heights of 0.25 and 0.5. For the larger particles the presence of a stationary flat bed is found not to influence the deposition rate. For particles <50 μm an increasing bed height, in general, is seen to lead to a decrease in the particle mean displacement from the pipe walls with time. For the smallest particles, the secondary flows in the pipe with a bed height of 0.5 are found to contribute to some re-circulation of the particles, with the mean displacement of particles from the pipe walls found to decrease with time before a further increase is observed.