ABSTRACT

The Office of Naval Research Tumblehome (ONRT) is a stealth destroyer ship that is characterized by a wave-piercing hull design as well as a large sail area. The literature indicates that the bare hull accounts for ∼80% of the ship's total resistance across the entire range of cruising speeds. A majority of the literature studies dealing with CFD simulations of the ONRT employ conventional body-fitted grids. Studies specifically dealing with ship resistance generally employ an incoming flow over a fixed body. In the present paper, we explore the feasibility of employing an embedded boundary-based CFD solver with a moving ship to estimate the total resistance. To this effect, we perform model-scale simulations of the ONRT bare hull using our inhouse code IITM-RANS3D. The solver employs the fast-fictitious-domain (FFD) method to model the ship as a moving embedded boundary over a Cartesian mesh. Two different cruising speeds which correspond to 15 knots and 30 knots at full-scale have been considered. The results have been validated in terms of the total resistance of the ship as well as the Kelvin wave-pattern generated by the vessel. The good agreement obtained establishes the feasibility of employing FFD-based CFD to estimate ship resistance.

INTRODUCTION

The Office of Naval Research Tumblehome (ONRT) is a Zumwalt class "stealth destroyer" featuring a Tumblehome wave-piercing hull design with a cruising speed of 30 knots (∼15.5 m/s) and a top speed of 32.4 knots (16.5 m/s). In contrast to flare hulls, the sides of the tumblehome hull slope inward into the waterline which minimizes the energy imparted by the hull to water which, in turn, minimizes its radar cross-section (RCS). Another notable feature of this ship is its large sail area, created by expansive flat surfaces and a deckhouse which houses a majority of the sensors and electronics.

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