Large-Eddy Simulations of Submarine Propellers

Abstract

High-fidelity, eddy-resolving, simulations of marine propellers are challenging due to the coexistence of moving and stationary elements within the computational box, as well as the need to accurately resolve the dynamics of wake structures such as the tip and hub vortices, which have an effect on the acoustic signature of underwater vehicles. Although an isolated propeller in open-water conditions can be simulated in a rotating reference frame, in a computation involving the body of an appended submarine, e.g., the relative motion needs to be properly treated. This increases the computational cost and reduces the accuracy/robustness of typical body-fitted approaches. In this work, an immersed boundary formulation is utilized to perform large-eddy simulations of a propeller in open-water conditions and in the presence of an upstream appendage at zero incidence. In such case, the requirement for the grid to conform to the moving body is relaxed—solution is locally reconstructed to satisfy boundary conditions—and efficient, conservative structured solvers can be used. This enables us to capture the detailed dynamics of the tip vortices and their footprint on the statistics of the wake. The influence of the upstream appendage is also assessed.