(577g) Euler-Euler and Euler-Lagrange Simulations of Heavy Particles Clustering in Homogeneously Sheared Gas

Particle-laden flows of sedimenting heavy solid particles or droplets in a carrier gas have strong inter-phase coupling even at low volume fractions. The slip velocity between phases lead to sustained clustering that can strongly modulate the overall flow. Simulations of homogeneously sheared flow are conducted in the Euler-Lagrange and Euler-Euler formalisms. We show that the formation of particle clusters involve three fundamental mechanisms: (1) the preferential concentration of inertial particles in the stretching regions of the flow (2) particle-trajectory crossing (PTC) and (3) a Rayleigh-Taylor instability due to the vertical stacking of particle-rich and particle-depleted regions. The Euler-Lagrange simulation method, based on particle tracking, capture all three effects but suffer from lack of scalability to industrial scales. Euler-Euler methods offer better scalability but require extreme care in the presence of PTC.