Multiphase Flow Dynamics: Investigating Complex Interactions in Fluid Mechanics

Abstract

Numerous modelling and simulation techniques for complicated multi-phase flow at the microscopic, mesoscopic, and macroscopic sizes are presented in this work. The capacity of each strategy to resolve scale and its interrelationship with other approaches are addressed. Applications are given using a liquid-gas system, where droplet dynamics, flow, turbulence, and combustion all interact at several scales in a complicated way. The effects of a very large number of droplets on turbulent combustion in two configurations within a fixed laboratory frame are investigated using large eddy simulation (LES). Next, a moving frame direct numerical simulation (DNS) is used to show the intricate dynamic interactions between droplets and response zones. In both the LES and the DNS, evaporating droplets are modelled in a Lagrangian macroscopic method, and have two- way couplings with the carrier gas phase. The lattice Boltzmann method (LBM) with different relaxation times is finally used to study droplet collisions. Since real-fluid equations of state are stable and able to handle large density ratios, the LBM handles multiphase flow.