ABSTRACT

This paper deals with the analysis of the confined water effects on the manoeuvring capabilities of a submarine. The analysis is carried out by using numerical simulations based on the RANS equations. The problem under consideration is an advancing submarine with constant speed and straight path at zero and non-zero drift/pitch angles, in open water, close to bottom and close to free surface conditions. The features of the flow around the submarine are described in terms of velocity and pressure fields; the computed force and moment coefficients are presented and compared with INSEAN measurements.

INTRODUCTION

The present work is part of a European research project supported by the WEAO, whose aims are: to improve numerical prediction methods for submarines manoeuvring in confined waters; to provide an experimental database of submarine manoeuvres in confined water; to validate computational fluid dynamic prediction of forces and moments on a body close to a boundary. To this aim, straight course, steady pitch and steady drift manoeuvres of a submarine operating in (i) open waters, (ii) close to a solid flat bottom and (iii) close to the free surface conditions are considered. In the latter case, otherwise calm water conditions are assumed. The submarine is appended with aft planes, two vertical rudders and forward horizontal planes; the operating propeller is accounted for by means of a suitable model. Analysis is carried out by means of numerical simulations: the numerical tool employed is a general purpose second order finite volume solver for incompressible turbulent free surface flow; the algorithm has been developed at INSEAN (Di Mascio et al. (2001), Di Mascio et al. (2005)). The theoretical assumptions and the numerical features of the INSEAN solver will be briefly described in the following section.

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