Effect of liquid–air interface on particle cloud dynamics in viscous liquids

Abstract

Three-dimensional numerical investigations have been performed to study the effect of liquid–air interface on particle cloud evolution in the stagnant pool of viscous liquid. Computations have been carried out using open-source computational fluid dynamics package open-source field operation and manipulation under different operating conditions. A hybrid multifluid–volume-of-fluid-based solver is used to identify the influence of liquid–air interface on particle cloud dynamics. Mainly, two different operating conditions have been considered in the present study, viz., falling particle cloud within the liquid and falling from the liquid–air interface. The effect of particle Reynolds number (Re) on cloud evolution has also been considered in the present study. The effect of the liquid–air interface on particle cloud dynamics has been qualitatively explained with the help of particle volume fraction iso-surface, liquid velocity vectors, and iso-Q-surface, and quantitatively explained with the help of average particle cloud velocity, penetration depth, plume half-width, and particle cloud mass. Proper orthogonal decomposition-based analysis has been used to explain the vortex structures generated in the viscous fluid for different cases. Releasing particle cloud from liquid–air interface decreases radial spreading as compared to the case of particle release within the liquid. Particle cloud evolution pattern is found to depend on particle Reynolds number only for the case with the liquid–air interface. The liquid–air interface's downward movement enhances and upward movement suppresses the spreading of the particle cloud, which subsequently alters the particle dispersion mechanisms in the later stages.