Simulation of a flow around a bluff body using Cartesian coordinates

This paper introduces a computational technique to compensate for the added numerical diffusion that is generated when uniform Cartesian coordinates are used to describe the flow around bluff bodies. Because of the staircase-like representation of the surface object, it was found that the added surface ”roughness” causes larger than expected separation region for some test cases (flow around a sphere, and flow around a cylindrical body). In order to control the velocity profile in the boundary layer, a new parameter blvr (boundary layer velocity ratio) is defined, and it is used to set the negative value of the viscosity along the surface. Extensive visualizations of flow past bluff bodies are performed using the present technique. Numerical solutions of the governing Navier-Stokes equations are carried out in a uniform Cartesian coordinates using a multi-directional finite difference scheme with a third-order upwinding. No explicit turbulence model is incorporated into the model, and the dependence of the solution on the blvr parameter is investigated.