Explicit interface treatments for compressible gas-liquid simulations

- Two approximate Riemann problem solvers (ARPS) without iteration are proposed.
- Ranges of application of implicit and explicit ARPSs are discussed.
- The explicit ARPSs facilitate the ghost fluid methods for interface computation.
- The interface treatments are efficient for large scale scientific computation.

Riemann-problem-solver-based ghost fluid method (GFM) provides us an effective manner to simulate compressible gas-liquid flows. Interfacial parameters are indispensable to define interface conditions and usually solved by an implicit approximate Riemann problem solver (ARPS). In this work, we design explicit pressure-based/velocity-based ARPS with a stiffened equation of state. Moreover, the ranges of application of these implicit and explicit ARPSs are discussed in detail. Equipped with these explicit ARPSs, it is more convenient to utilize the idea of modified GFM (MGFM) or practical GFM (PGFM) to define ghost fluid states in numerical applications. Results from the proposed explicit method compare well with that from the implicit method. Especially the PGFM with the present explicit velocity-based ARPS is more widely used and more efficient for large scale scientific computation.