Two Phase Level-Set/Immersed-Boundary Cartesian Grid Method for Ship Hydrodynamics

Recent progress at IIHR on the development of CFDShip-Iowa version 6 is presented. Current focus is on a sharp interface Cartesian grid method for the large-eddy simulation (LES) of turbulent two-phase incompressible flows. In this method, the level set formulation for two-phase incompressible flows is adopted. The density and pressure jump conditions across the interface (the latter due to surface tension and gravity) are treated in a sharp interface manner using the ghost fluid method. Complicated geometries immersed in the computational domain are handled with a sharp interface immersed boundary method. For LES, the Lagrangian dynamic Smagorinsky subgridscale model is used. Several approaches for capturing high Reynolds number boundary layers in a Cartesian grid layout are discussed. Simulations of several ship geometries, including the Wigley hull, DTMB model 5365 (Athena R/V), and surface combatant DTMB model 5415, have been carried out on relatively coarse Cartesian grids. Wave field patterns are successfully compared with experimental data and other computational results. To demonstrate the potential of coupled curvilinear/Cartesian grid methods, a case has been set up for model 5415 which utilizes the outer boundary layer velocity solution from a body-fitted RANS solver as boundary conditions for the immersed boundary method; very promising results have been obtained. The proposed developments needed to simulate high-Reynolds number boundary layers are briefly discussed.