CFD PREDICTION OF THE FLOW AROUND A SUBMARINE MANOEUVRING IN OPEN AND CONFINED WATER

The turbulent flow fields around a submarine in steady manoeuvre are computed by means of a RANSE solver. Three different pitch angles (namely 0, +5 and -5 degrees) in both open and confined water conditions are considered. Effects of confined water are analysed by taking into account the presence of a bottom wall. Computation of the flow field around the submarine in steady straight course close to a free surface is also performed. Simulations are carried out at Reynolds number equal to 6.27 × 106 and Froude number equal to 0.2. The numerical method used is a finite volume second order accurate scheme, where convective fluxes are computed by means of an ENO type scheme, whereas diffusive fluxes are evaluated by a classical second order centered formula; turbulent effects are taken into account by using the one-equation Spalart-Allmaras model; free surface effects are simulated by a single-phase level set method. Discretization of the physical domain is achieved by means an overlapping grid approach. Computed longitudinal and vertical forces as well as pitch moment coefficients are presented for all the simulations. Examples of the computed flows, in terms of velocity fields, pressure distribution and streamlines patterns are presented.