LES of the Flow Past an Inclined 6:1 Prolate Spheroid

Paper in proceeding, 2009

Flows around maneuvering ships, submarines and underwater vehicles are usually quite complicated, and often experience three-dimensional open flow separation resulting in unsteady forces and moments that may be detrimental to ship performance. The objective of this investigation is to support more applied maneuvering studies by investigating the computational model performance with respect to approaches to flow simulation methodologies, turbulence modeling, grid resolution and the effects of tripping devices often used in experimental studies. To study these issues simulations are performed of the flow past a 6:1 prolate spheroid, tripped at the nose, and experimentally studied in a series of papers by Simpson et al. Here, we compare predictions from Reynolds Averaged Navier Stokes (RANS), Detached Eddy Simulation (DES) and Large Eddy Simulation (LES) models with experimental data. For the LES computations, different subgrid models are utilized and since the experimental study is carried out using a tripped model, a simple trip model is also developed and tested together with the LES models. Large scatter between the predictions is found, with the DES model and one of the trip-ped LES model showing very good agreement with the data. For LES, the modeling of the trip, which is usually not considered, appears as important as that of the near wall handling and modeling in wall-modeled LES.