High-speed planing hull drag reduction using tunnels

Forward speed is perhaps the most important parameter in the design of a planing hull. The speed strongly influences the drag and thus the energy supplied by the engine of the ship. Employment of an appropriate drag reduction strategy plays an important role in the design of these hulls. The flow around a Cougar high-speed planing hull was numerically simulated and the results were compared against experiments available in the literature. To reduce the total drag, two tunnels were introduced at the bottom section of the original Cougar hull. The weight and center of gravity of both hulls remained the same. An unstructured mesh was generated in the computational domain around the hull and a Re-Normalization Group K-ε formulation was used to model the turbulence. To capture the free-surface of the flow around the hull, the volume-of-fluid model was applied. The drag forces of both the original and modified Cougar hulls were obtained for various forward speeds, corresponding to the original hull length-based Froude numbers ranging from 1.00 to 5.62. The results show a 14% reduction in total drag for the modified hull at the forward speed of 60 knot.