OVERLAPPING CONTROL-VOLUME APPROACH FOR CONVECTION-DIFFUSION PROBLEMS

This paper introduces a finite volume method to solve 2D steady state convection-diffusion problems on structured non-orthogonal grids. Over lapping control volumes (OCV) are used to discretize the physical doma in and the governing equations are solved without transformation. An i soparametric formulation is used to compute diffusion and for upwindin g. Four test problems are solved using this and other schemes. The mod elling of diffusion in OCV seems very effective even on distorted mesh es. The convection modelling in OCV is found to be sec end-order-accur ate, like QUICK, on regular meshes. Although its accuracy is slightly inferior to the latter on rectangular grids, its faster convergence gi ves it a better overall performance. On non-orthogonal grids, OCV give s better accuracy for a large and practical range of Peclet numbers th an does QUICK applied to the transformed equations using the conventio nal five-point diffusion modelling. The results obtained also demonstr ate that the scheme reduces false diffusion to a considerable extent i n comparison with the power-law scheme.