Analysis of interfacial sharpening techniques for upwind-biased shock- and interface-capturing methods in diffuse interface simulations of shock-dominated compressible two-phase flows*

In compressible two-phase flows, WENO-type upwind-biased spatial discretization schemes are a popular choice to provide sufficient numerical dissipation for stabilizing material interfaces and shock discontinuities. In contrast to shocks, material interfaces are not inherently self-sharpening. Thus, in the presence of numerical dissipation, material interfaces will continuously diffuse unless interfacial sharpening is applied. In this work, we investigate the interplay of WENO-type spatial discretization schemes and interfacial sharpening techniques in the five-equation diffuse interface model. We consider multiple variants of the conservative diffuse-interface method and compare them against the well-established THINC scheme and the baseline WENO scheme without interfacial sharpening. We consider 2D and 3D canonical test cases of shock-dominated compressible flows with large density ratios. We analyze the interaction between aforementioned interface regularization techniques and the underlying WENO-type discretization and evaluate how the interface regularization affects the temporal interface evolution.