Book Description
A Volume of Fluid (VOF) multiphase numerical study was conducted using the commercial simulation software ANSYS Fluent to understand the effects of compressibility on droplet breakup in the laminar flow regime. A 2D axisymmetric domain which consists of four subdomains was used for the simulations. Validation of the setup and mesh was conducted by comparing to analytical shock tube equation, Engel’s, and Boger et al.’s work. Two regimes of flows, subsonic and supersonic, were used and were obtained by selection of the operating pressure, velocity, density, dynamic viscosity, and temperature to keep the Reynolds, Weber, and Mach numbers at fixed values between cases. The Reynolds number was held constant at 100. Significant differences within the stripping breakup mode between the supersonic and subsonic cases for similar values of the Weber and Reynolds numbers were observed. The difference was observed in terms of droplet deformation, droplet deformed shape, and droplet lifetime. A Weber number effect is also observed to influence the droplet lifetime. Differences in the pressure distribution were found to drive the different degrees of vertical elongation while the viscous stress mainly acts to bend the droplet downstream. The pressure was found to be the major factor while viscous stress acts as the smaller factor in the physics during most of the deformation process, but viscous stress shows to be the major role at the beginning of the process. Comparison to the solid sphere case provided confirmation of the pressure distribution difference observed between supersonic and subsonic case was expected. Comparison to solid sphere also shows how droplet deformation itself plays a role in effecting the flow field