Numerical investigation of the tunnel aperture on drag reduction in a high-speed tunneled planing hull

Abstract

One of the methods for reducing drag is inducing a change in the shape of the body due to making longitudinal side tunnels on the hull body. In this method, the usual shape of a specific mono-hull is changed into tunneled one keeping the geometric parameters, including deadrise angle, keel line, beam width, and the hull length, constant. Various geometric parameters are effective on drag reduction of different sections of the tunnel while designing and manufacturing the hull. To obtain an optimum shape for the tunnel, this study has attempted the influence of the size of the tunnel aperture on hydrodynamic parameters of the hull. For this purpose and through considering the moving mesh, numerical simulation of the problem by means of finite volume method has been employed, using FLUENT commercial software. For turbulence modeling, k-ε model, and for simulating the free surface, the volume of fluid two phase model has been used. In addition, remeshing and smoothing methods were employed for moving mesh. The presented results show that, forming a tunnel in the base hull could cause a reduction in the total drag in high-speed planing hulls and in the vessel draft over the whole range. Furthermore, in high Froude number, a reduction in the size of the tunnel aperture (up to a specific amount) could lead to a decrease in the total drag.