Moving air-water interface on no-slip solid walls for high-speed planing hulls

In this study, the classical 'moving-contact-line' problem associated with the no-slip boundary condition (BC) is examined, with a particular focus on large-scale, high Reynolds number turbulent ship flows. Numerical ventilation is one of the main issues reported for the computational prediction of the high-speed small planing craft using the Volume-of-Fluid (VOF) method. A numerical strategy is presented to resolve this issue with a wave blanking distance defined and used when solving the VOF equations, which is chosen based on the y+ values and the velocity profiles in the boundary layer. A series of numerical tests are conducted using a slamming plate and a stepped high-speed planing hull. The numerical experiments show that if the blanking distance is y+<30 (inside the buffer and viscous sublayers), the air-water interface on the wall will be unstable and numerical ventilation will occur. For the blanking distance y+>30 (outside the buffer layer), the air-water contact line is smooth and air entrainment can be avoided. It is suggested that the blank distance needs to satisfy 30.0<y+<200.0 in consideration of accuracy and stability, and a value of y+∼100.0 can be used in practice.