Synchronous and asynchronous water-entry impacts of two-dimensional asymmetric catamarans

The water-entry dynamics of catamarans are critical in marine engineering due to their complex hydrodynamic behavior and potential for severe slamming loads. This paper investigates the hydrodynamic mechanisms of two-dimensional asymmetric catamarans during both synchronous and asynchronous water-entry situations. The numerical model is based on an immersed boundary ghost cell method combined with the gradient augmented level-set approach. The aim is to analyze the effects of key parameters such as hull spacing, bottom deadrise angle, and drop height on the slamming loads and free-surface evolution. The interaction between the two hulls significantly impacts the pressure distribution. A maximum pressure difference of 7% is observed at certain spacings. When the spacing reaches s/h = 2, the pressure interaction between the hulls is minimal, indicating that the hulls operate almost independently. The pressure at the starboard demi-hull increases by 70% with rising drop heights during synchronous entry, exhibiting pronounced Wagner-type impacts. In asynchronous entry, a 20% pressure increase is observed at the starboard demi-hull with a height difference, showing distinct impact patterns. As the deadrise angle increases from 7° to 20°, the peak pressure at the starboard demi-hull during synchronous water entry decreases by 60%. Increasing the bottom deadrise angle reduces pressure peaks and alters the pressure curve patterns. This research provides valuable insights for optimizing catamaran design and enhancing its operational safety and efficiency.