Investigation on cylinder water entry in regular wave field using large eddy simulation

Objects entering water into a wave instead of calm water involve complex multiphase flow phenomena. Large eddy simulation (LES) is used to numerically investigate the water entry of a small-scale cylinder in a regular wave field. A free-motion model of the cylinder is established using the sliding grid technique. The velocity boundary wave-generation method is employed, where a second-order Stokes wave analytical solution is applied at the inlet, and wave-absorbing sources are added in regions far from the water entry region. By comparison with the experimental results, the numerical scheme in this study can capture the cavity evolution, movement of the entering body, and even the closure of splashes. The influence of the four wave phases on the vertical entry and various water entry angles are investigated. The cavities are primarily influenced by the velocity field direction and wave slope in different wave phases. Based on this, a theoretical correction approach has been proposed, showing good agreement with the numerical results. The different characteristics of the deep seal for the against-wave entry and following-wave entry cases are discovered. The multiphase flow field caused by vertical entry is more complex than inclined entry because of the splash difference. The cylinder drag is primarily derived from the contact between the cylinder and asymmetrical cavity.