| The development of a computer model for simulation of incompressible turbulent flow and heat transfer over rough surfaces using the discrete element method is presented. The discrete element roughness model is implemented into an existing incompressible Navier-Stokes algorithm. This algorithm is a finite volume, incompressible Navier-Stokes solver which uses artificial compressibility and the Roe approximate Riemann solver, also referred to as the flux difference split method. The equations solved in this code were modified to include surface roughness effects in the flow. Details of the roughness effects on the flow are modeled empirically instead of being resolved in the computational geometry. The roughness element from drag and heat transfer are treated as volumetric sink and source terms respectively.; Cases were tested for flow and convective heat transfer over smooth and rough flat plates with different free stream velocities and roughness distributions. Also, flow computations were performed for an axisymmetric body with an inflected curved stern and a NACA-0012 airfoil.; The rough flow prediction model was observed to simulate the effects of surface roughness accurately; in one case flow separation was indicated. In all cases the computed effects of surface roughness were observed to yield higher skin friction than the equivalent flow over a smooth surface. For the case of computed heat transfer over the flat plate, roughness was seen to increase heat transfer. |
