Simulating turbulent transition using Large Eddy Simulation with application to underwater vehicle hydrodynamic modelling

Abstract

Large Eddy Simulation (LES) has been widely used by the aerospace community in order to model laminar separation bubbles and other low Reynolds number phenomena. In maritime-related applications this family of turbulence modelling techniques has typically been used to model unsteady cavitation. Present work aims to apply it to develop first-hand experience with modelling laminar separation bubbles using LES in OpenFOAM, specifically looking at the effects of the choice of the subgrid model. The investigation is carried out on the SD7003 2D foil section, for which PIV flow field measurements, as well as reference CFD results, are available. Four different popular LES models are tested: Smagorinsky, dynamic $k$-equation, wall-adaptive (WALE), and implicit (ILES). The ultimate goal of this work is to apply the established methodology to model flows on underwater vehicle appendages, as well as propellers, which have been reported to experience noticeable amounts of laminar flow when operating at model-scale Reynolds numbers. These flows experience complex, unsteady hydrodynamic phenomena, such as tip and root vortices, laminar separation bubbles, and are affected by onset turbulence. Thus, studying them with LES could lead to improved predictions compared to the previous work by the authors which relied on using RANS transition models to simulate the flow past underwater vehicle geometries