Numerical Analysis and Geometric Assessment of Air Layer Distribution in a Ventilated Planing Hull in Calm Water

The issue of resistance reduction through hull ventilation is of particular interest in contemporary research. This paper presents multiphase computational fluid dynamics (CFD) simulations with 2-DOF motion of a planing hull. The original hull was modified by introducing a step to allow air ventilation. Following an assessment of the hull performance, a simulation campaign in calm water was conducted to characterize the hull at various forward speeds and air insufflation rates for a defined single step geometry. Geometric analysis of the air layer thickness beneath the hull for each simulated condition was performed using a novel method for visualizing local air thickness. Additionally, two new parameters were introduced to understand the influence of spray rails on the air volume beneath the hull and to indicate the primary direction of ventilated air escape. A validation campaign and an assessment of uncertainty of the simulation has been conducted. The features offered by the CFD methodology include the evaluation of the air layer thickness as a function of hull velocity and injection flow rate and the air volume distribution beneath the hull. The air injection velocity can be adjusted across various operating conditions, thereby preventing performance or efficiency loss during navigation. Based on these findings, the study highlights the benefits of air insufflation in reducing hull resistance for high-speed planing vessels. This work lays a robust foundation for future research and new promising topics, as the exploration of air insufflation continues to be a topic of contemporary interest within naval architecture and hydrodynamics.