(78c) Role of Mass Loading on the Onset of Flow Modulation in a Dilute Turbulent Slurry in Eulerian-Lagrangian Simulations

The modification of turbulent structures by point particles suspended in a fluid flow is of interest to pipeline design for oil and slurry transport. However, the point at which suspended particles start modulating the carrier flow remains poorly understood. To address this knowledge gap, we analyze the effect of point particles with different parameters on the carrier fluid statistics and near-wall coherent structures. The investigation is conducted in the configuration of particle-laden turbulent channel flow at a friction Reynolds number of 180, particle volume fraction varying from 1% to 6%, and mass fraction varying from 3% to 50%. Simulations use a Eulerian-Lagrangian strategy (EL) based on the volume-filtering method and has been previously thoroughly tested in massively parallel simulations of particle-laden flows. Depending on the volume fraction and particle diameter, the total number of tracked Lagrangian particles ranges between 180 thousand and 11 million. Statistics are collected and compared to statistics from auxiliary simulation with no particles. The simulations reveal that significant flow modification occurs only in cases where the mass loading approaches 50%. In such cases, we observe a reduction of the friction coefficient by about 15% and fluid mass flow rate by about 5%. Further, we show that particles with friction-based Stokes number below 1 remain randomly distributed throughout the channel, whereas particles with friction Stokes number about 7.5 display large inhomogeneity characterized by significant clustering and the tendency to accumulate near the walls.

This work is supported by ACS PRF# 62195-DNI9