Numerical Simulation of Viscous Flows Around a Surface Combatant Model at Different Drift Angles Using Overset Grids

Abstract

Viscous flows around ship hull is of great complexity, and when the ship is advancing with drift angles, the flow field can be more complicated. In this paper, the viscous flow field around an obliquely towed surface combatant DTMB 5512 is computed using the unsteady Reynolds-averaged Navier–Stokes (URANS) method. The numerical simulations are carried out by the in-house CFD solver naoe-FOAM-SJTU, which is developed on the open source platform OpenFOAM. To refine local grids and simulate dynamic ship motions, the overset grid approach is applied. Grid convergence study is first performed at straight-ahead towed condition with three sets of grid number and the results show monotonically convergence. Six different drift angles for the DTMB 5512 model at Froude number of 0.28 are simulated and the predicted hydrodynamic forces and flow field are presented. During the simulation, the ship hull is free to trim and sinkage at a free surface environment. As for straight-ahead towed condition, the total resistance coefficient and flow field, i.e., wave pattern and wake region, between this work and the experiment are compared. Both force coefficients and flow field show good agreement with the available experimental data. For oblique towed conditions, the lateral force, yaw moment and the derived hydrodynamic derivatives are also presented and compared with the experimental results. The variation of wave pattern and wake region at different drift angles are presented and analyzed. The results show that the current approach can be an effective tool to predict the viscous flows and hydrodynamic loads for oblique towed ships.