The dynamics of inertial particles in under-expanded jets: A numerical study

Despite decades of progress towards understanding and modeling the dynamics of inertial (heavy) particles suspended in turbulent flows, much less attention has been made to flows with significant gas-phase compressibility. In this work, three-dimensional Eulerian–Lagrangian simulations of particle-laden under-expanded jets are performed to study the dynamics of inertial particles in compressible flows. The simulation configuration is guided by a companion experimental study: The dynamics of inertial particles in underexpanded jets: An experimental study. The gas-phase equations are solved in a high-order, energy stable finite difference discretization. An immersed boundary method combined with a levelset approach is employed to model the nozzle geometry. Particles are injected within the nozzle with velocity sampled from a random Gaussian distribution informed by high-speed imaging in the companion experiment and diameters sampled randomly from a lognormal distribution. The focus of the present work is on the ability of existing drag models to capture particle dynamics through a series of compressions and expansions (Mach diamonds).