Numerical Analysis of Wide-Angled Diffusers in Turbulent Flow

The mathematical model of steady turbulent flow in wide-angled conical diffusers is presented. Static pressure distribution resulting from the numerical solutions is more flattened than the experimental data, due to the underestimation of normal turbulent stresses. On the contrary, the shear stresses are generally overestimated: The opposing effects of the stresses counterbalance in the mean kinetic energy and momentum analysis. The spatial distribution of stream lines is well predicted as well as the detailed characteristics of recirculating region, as a result of the choice of the wall function. The discrepancies in the predictions of some quantities confirm the need to refine the turbulence modeling when recirculating regions are present, as in wide-angled diffusers.