IBM/ICM method for interactions between moving bodies and free surfaces

The IBM/ICM method is developed to simulate the interactions between moving bodies and free surfaces. This method is a combination of Immersed Boundary Method (IBM) and Interface Capture Method (ICM), inheriting the IBM's capability of using non-body conformal grids to represent the effect of a moving body in the flow by only adding a pseudo body-force in the right side of Navier-Stokes equations, as well as the capability of ICM, i.e. VOF, to capture the interface between two immiscible fluids. In the current paper, the Lagrange-multiplier based IBM method is employed and the volume of fraction (VOF) is introduced as an indicator function to mark the different fluids. The numerical method is validated by the case of high-speed impact by a horizontal circular cylinder, which exhibits a wide range of dynamical response characteristics, i.e. the formation of a cavity and induced pressure waves in the late stages of the cavity collapse, depending primarily on the projectile's impact velocity.