Pressure-based compressible two-phase model for continuous process of underwater explosion

This study presents a model to simulate the continuous process of underwater explosions (UNDEX), aiming at exploring the dynamic flow starting from the explosive charge to capture both the emitted shock wave and the oscillation of the bubble. A compressible two-phase flow solver implemented in OpenFOAM is employed, solving the Navier-Stokes equations via a pressure-based algorithm for the coupling of velocity, pressure, and density. The behavior of the explosive gas is simulated with the Jones–Wilkins–Lee equation of state in a tabulated form to allow for the coupling with the pressure-based algorithm. To accurately capture the gas-water interface, the compressive volume of fluid method is utilized, and a modified formula for the compressive flux is proposed to circumvent numerical wrinkles at the bubble interface. The improved model is validated using various test cases, including UNDEX in the free field and near the free surface. Comparisons with experimental data, analytical solutions, and results from a fully explicit algorithm are conducted. The results demonstrate that the present model is an effective tool capable of simulating shock wave propagation and accurately capturing bubble oscillation in UNDEX.