A numerical simulation of full-appended submarine is presented. This kind of simulations constitutes a challenging task due to the geometrical complexity of the appendages present and their relative movement. In order to obtain useful results the underlining numerical scheme must be accurate and it must be coupled with a suited numerical grid. The turbulent flow around the full appended submarine is simulated by means of the numerical integration of the Unsteady Reynolds Averaged Navier–Stokes Equations (URANSE): the numerical scheme used is based on a finite volume technique with pressure and velocity co-located at cell centers. For the viscous terms a standard second-order centered scheme is adopted, whereas for the inviscid part three different schemes can be chosen: a second-order ENO (essentially non–oscillatory) scheme, a third-order upwind scheme, and a fourth-order centered scheme. The physical time derivative in the governing equations is approximated by a second-order accurate, three-point backward finite difference formula. In order to obtain a divergence free velocity field at every physical-time step, a dual- or pseudotime derivative is introduced in the discrete system of equations. The convergence ratio for the inner iteration is accelerated by means of local time stepping, an implicit Euler scheme with approximate factorization and a multigrid technique. In order to resolve the boundary layer turbulent flow a body-conformal grid is adopted. In the authors approach a “dynamic overset grid” technique is used: each geometrical appendage of the whole geometry is discretized with a set of structured body-conformal grid blocks with partial overlapping each others (Chimera approach). This approach preserves the quality of each structured grid block and has sufficeint flexibility to deal with very complex geometry.

In the full paper we present numerical simulations of full appended submarine with moving appendages.