URANS simulations of catamaran interference in shallow water

This paper investigates the interference effects of wave systems on a multi-hull vessel in shallow water. A numerical analysis is made using the URANS code CFDSHIP-Iowa V.4 on the DELFT Catamaran model 372. The test matrix for numerical computations includes two separation distances (s = 0.17; 0.23) and the depth values of h/T = 8.2, 2.5 and 2, at several speeds ranging within FrH = 0.775–1.739. Numerical results are compared with the experimental data of the Bulgarian Ship Hydrodynamic Center, and verification and validation for resistance, sinkage and trim are also performed. Results show that, at critical speed (FrH ≈ 1), the presence of a finite depth significantly affects the catamaran total resistance, which, in shallower water, increases considerably with respect to deep water. At low h/T, small effects of the water depth on resistance occur at subcritical and supercritical speeds. The interference effects seem to be more relevant in shallow, rather than in deep water, with maximum IF values registered at critical speeds (FrH ≈ 1). Similarly to deep water, the lower the separation distance the greater the interference value. Moreover, in shallow water some negative interference is observed at Fr > 0.5. Wave patterns and wave profiles are analyzed and a comparison is made between several configurations of catamaran and a mono-hull vessel, in order to analyze how water depth and separation distance determine resistance and interference. Finally, a vortex instability study is also included.

[1]  Anthony F. Molland,et al.  Resistance and wash measurements on a series of high speed displacement monohull and catamaran forms in shallow water , 2004 .

[2]  A. Chwang,et al.  Trailing vortices in a free-surface flow , 2002 .

[3]  Riccardo Broglia,et al.  Numerical simulation of interference effects for a high-speed catamaran , 2011 .

[4]  Jun Shao,et al.  Quantitative V&V of CFD simulations and certification of CFD codes , 2006 .

[5]  A. Roshko.  On the Wake and Drag of Bluff Bodies , 1955 .

[6]  P. Moin,et al.  Eddies, streams, and convergence zones in turbulent flows , 1988 .

[7]  Frederick Stern,et al.  Vortical Structures and Instability Analysis for Athena Wetted Transom Flow with Full-Scale Validation , 2012 .

[8]  Kazuo Suzuki,et al.  Computation of wave-making resistance of a catamaran in deep water using a potential-based panel method , 2007 .

[9]  Benjamin Bouscasse,et al.  Calm Water and Seakeeping Investigation for a Fast Catamaran , 2011 .

[10]  Anthony F. Molland,et al.  Resistance experiments on a systematic series of high speed displacement catamaran forms: variation of length-displacement ratio and breadth-draught ratio , 1994 .

[11]  Ronald W. Yeung,et al.  Multihull and Surface-Effect Ship Configuration Design : A Framework for Powering Minimization , 2008 .

[12]  Som Deo Sharma,et al.  Wave Reduction by S-Catamaran at Supercritical Speeds , 2003 .

[13]  Stefan Mayer,et al.  Large Eddy Simulation of a Flow Past a Free Surface Piercing Circular Cylinder , 2002 .

[14]  R. Zamora-Rodríguez,et al.  Analysis of the wave system of a catamaran for CFD validation , 2007 .

[15]  Ralph Noack,et al.  SUGGAR: A General Capability for Moving Body Overset Grid Assembly , 2005 .

[16]  Frederick Stern,et al.  CFD analysis of broaching for a model surface combatant with explicit simulation of moving rudders and rotating propellers , 2012 .

[17]  David E. Hess,et al.  Computational Hydrodynamic Tools for High-Speed Sealift: Phase II Final Report , 2008 .

[18]  Tim Gourlay.  From cargo ships to skimboards − what happens to the wave resistance hump in shallow water? , 2012 .

[19]  L. Sigurdson.  The structure and control of a turbulent reattaching flow , 1995, Journal of Fluid Mechanics.

[20]  Mustafa Insel,et al.  AN INVESTIGATION INTO THE RESISTANCE COMPONENTS OF HIGH SPEED DISPLACEMENT CATAMARANS , 1992 .

[21]  Robert Latorre,et al.  Wave resistance for high-speed catamarans , 2004 .