A Correction Scheme For Point-Particle Modeling of Droplets and Spray Systems

Abstract

Modeling of spray systems using the point-particle approach requires estimation of the undisturbed fluid flow quantities such as velocity, pressure, species mass fraction, and temperature at the droplet location, to accurately capture the droplet dynamics. However, in a typical two-way coupled computation, the droplets affect the fluid flow through mass, momentum, and energy exchange, and disturb the flow. This self-disturbance effect is significant for droplet sizes that are on the same order or larger than the grid resolution, which in practice is common in spray studies, even for a point-particle based approach. A general formulation that accounts for the self-disturbance created by the dispersed droplets in obtaining the undisturbed fluid flow for accurate computation of the force closure, thermal heating, and evaporation is derived. This self disturbance-corrected approach is evaluated for two simple test cases of (i) single droplet held fixed in a uniform flow of hot fluid, and (ii) gravitational settling of a droplet in a quiescent, hot fluid to show very good predictive capability. The approach is straightforward and can be applied to any numerical formulation for spray systems.