A PROPOSAL OF THE CALCULATION TECHNIQUE FOR FLOW AROUND A CIRCULAR CYLINDER THROUGHT THE AIR-WATER INTERFACE WITHOUT TRACKING THE INTERFACE

Abstract

 Since physical properties such as density are different between the gas and liquid phases, it is common to solve the fundamental equations with tracking the gas-liquid interface and clearly separating the gas and liquid phases. The fluid force acting on a solid which penetrates the gas-liquid interface differs in magnitude between the gas and liquid phase. The fluid force calculated by the Immersed Boundary Method (IBM), which estimates the fluid force acting on the solid surface from physical quantities such as the velocity and pressure of the surrounding fluid, becomes unstable due to this fact. In this study, we proposed a calculation method of the Navir-Stokes equations with the pressure term transformed to φ = p/ρ in the equation of motion to avoid computational problems caused by the pressure discontinuity at the gas-liquid interface and to simplify the computational algorithm. As an example of the application of these methods, flow analysis around an oscillating cylinder that penetrates the gas-liquid interface was performed.