Unstructured Nonlinear Free Surface Simulations for the Fully-Appended DTMB Model 5415 Series Hull Including Rotating Propulsors

Nonlinear free surface simulations around realistic geometries, such as the DTMB Model 5415 Series hull, are a necessary step to achieve the goal of simulation of maneuvering surface vessels. As part of this effort, researchers in the Computational Simulation and Design Center at Mississippi State University have developed and parallelized a three-dimensional unstructured code, , which solves the incompressible Reynoldsaveraged Navier-Stokes equations using a node-based flux differencing finite volume method with Roe-averaged variables. The simulations produced by this code realistically capture turbulent flow and vortices arising from bulbous bows and tips of propulsors and rudders and can model the rotation of the propulsors accurately. Because the code uses unstructured grids, the code is applicable to a wide range of geometries, including those with shafts and struts, and can solve the flow through small gaps such as those between the rudder and the boot. Current research efforts include the addition of nonlinear free surface capabilities to this code. A nonlinear free surface is obtained by solving the kinematic free surface boundary condition, imposing the resulting hydrostatic pressure di stribution onto the boundary for the Navier-Stokes solver and moving the grid to match the free surface while conforming to any geometry that intersects the free surface. The current free surface implementation is loosely coupled with the Navier-Stokes solver and makes the assumption that the flow is steady-state.