Session: 05-07-02: CFD Development and V&V

Paper Number: 131305

131305 - Interface Sharpening of Two-Phase Flows on Unstructured Meshes 

The purpose of this study is to extend current state of the art methods for sharpening the interface between two immiscible fluids into unstructured simplex meshes. Such methods have emerged as an attractive means to track interfacial dynamics between two fluids because of their parameterization and control of interface thickness. Existing LS/PF representations of these two-phase flows conserve the mass of both phases, appropriately bound the volume fraction, and are accurate, but rely on structured quadrilaterals for the calculation of interfacial numerical fluxes. Unstructured meshes, which can fit complicated domains and provide more accurate solutions to conserved variable fields, nonetheless demand a more nuanced approach towards the computation of gradient variables. This study describes a formulation in which gradient/divergence fields are found by integrating along boundaries of dimension-agnostic control volumes. These fields inform an interface regularization term that significantly counteracts artificial numerical diffusion. The proposed methodology is implemented into Ablative Boundary Layers At The Exascale (ABLATE), an open-source software package being developed to simulate hybrid rocket motors. Examples of sharp volume fraction interfaces, important to simulation of multiphase flows, are compared to conventional diffuse upwinding methods. With this method, evolving fronts can be sharpened regardless of the embodied structure or dimensionality of the computational grid. The proposed method is conservative and simple to implement.

Presenting Author: Joseph Marziale University at Buffalo, State University of New York