Assessment of Numerical Methods for Two Phase Shear Layers

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. The performance of 6th order staggered, compact finite difference method with the 5-equation model, 2nd interface sharpening, and localized continuum surface force method for surface tension modeling is evaluated for basic flows related to the two-phase mixing layer. 8th-order filtering is currently used for robustness with the longer-term objective of minimizing numerical dissipation. Surface tension test cases of a high-density stationary droplet and Laplace number = 24,000 droplet show low spurious current levels and 2nd order convergence of spurious currents with refinement. This combination of methods is robust for high density ratios, showing promise to simulate shear-induced breakdown of a temporal two-phase shear layer.

Funded by the US Department of Energy PSAAP-III Program at Stanford University (Award DE-NA0003968) and by U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, Department of Energy Computational Science Graduate Fellowship (Award Number DE-SC0022158).