FURTHER ASSESSMENT OF NUMERICAL ANNULAR DUMP DIFFUSER FLOW CALCULATIONS.

A further study has been conducted for a model dump diffuser. The results obtained from several flow calculations using the standard k minus epsilon turbulence model on two 12 refs. of grid distribution are presented. It is found that a coarser grid distribution may yield a better agreement between the numerical prediction and the experimental data. Also, a lower order finite difference scheme may produce a more favorable theory-data comparison than the higher order ones. The findings suggest that the standard k minus epsilon two-equation turbulence model is inadequate for predicting the detailed features of the flow studied here. The zonal grid approach, which divides the whole flow domain into several subregions and generates the grid system in each subregion according to its own need, is also much needed. Both the physical modeling and the numerical grid generation needs require extensive research effort.