Investigation of fine viscous flow fields in ship planar motion mechanism tests by DDES and RANS methods

Abstract

The fine large separated flow is a focus in the naval architecture and ocean engineering. In the present study, the CFD solver, naoe-FOAM-SJTU, coupled with delayed detached-eddy simulation (DDES) and Reynolds Averaged Navier-Stokes (RANS) is adopted to simulate the fine viscous flow field in the ship planar motion mechanism (PMM) tests for the benchmark model Yupeng Ship. This paper compares the time histories of forces/moment acting on the hull and their oscillation frequency obtained by Fast Fourier Transform. The predicted results are in good agreement with the experimental data. By comparing the turbulent kinetic energy (TKE) and eddy viscosity coefficient calculated by both numerical methods, the results show that the TKE and eddy viscosity coefficient obtained by DDES method are much less than that achieved by RANS approach. The capacity of four vortex identification methods to capture vortex structures is analyzed in this paper, indicating that the third generation of vortex identification methods (ΩR and Liutex methods) are more suitable for analyzing the flow mechanism in the viscous large separated flow field. The axial Liutex and streamlines on the cutting planes are used to depict the flow around the hull.