Assessment of Localized Artificial Diffusivity and Interface Sharpening for Modelling a Two-Phase Mixing Layer*

Atomization occurs when a liquid jet from a nozzle is discharged into a stagnant or moving gas causing the gas-liquid interface to become unstable and break up into a collection of droplets. The objective is to simulate a simplified problem of a 3D, planar two-phase mixing layer between a co-flowing liquid and high-speed gas stream in a compressible regime, relevant to rocket propulsion. Localized artificial diffusivity (LAD) method is a diffuse interface method that combines explicitly adding artificial fluid properties to physical transport properties in regions around the two-phase interface and shocks with high-order compact finite difference schemes to produce stable, low-cost, and high accuracy simulations.  The addition of interface-sharpening treatment allows the two-phase interface to remain sharp. This extended LAD method has potential to accurately simulate the two-phase mixing layer with substantial density differences, but its performance in basic flows related to the two-phase mixing layer must be determined. The present work evaluates the performance of the extended LAD method in treating basic phenomena related to the breakdown of the gas-liquid interface through a series of model problems, including shear-induced breakdown of a temporal two-phase shear layer.