Masayoshi Okamoto

Prediction of streamline curvature effects on wall-bounded turbulent flows

Abstract A low-Reynolds-number second-moment closure without wall-reflection redistribution terms is tested in wall-bounded turbulent flows with streamline curvature. The turbulence model was previously shown to give good predictions for a fully developed channel flow, boundary layers in zero, adverse and favorable pressure gradients, plane and round jets, and flows with wall blowing and suction. In the present study, the model is used to calculate two fully developed curved channel flows and four boundary layers on curved walls. The turbulence model captures main features of the stabilizing and destabilizing effects of streamline curvature, though some notable discrepancies between the predictions and measurements are present in boundary layers on convex walls.

Direct Numerical Simulation for Streamwise Rotating Turbulent Flow Through a Square Duct

The direct numerical simulation for the turbulent square duct flow with the streamwise system-rotation is performed. The streamwise system-rotation effect is closely related with the secondary flow in the square-duct cross-section and the cyclonic secondary flow is strengthened as the system angular velocity increases. The distribution of the mean quantities is affected by the rotating secondary flow. Moreover, it is found that the two-point correlations in the cross-section and propagation velocity profiles, which are estimated from the two-time and two-point correlations, change drastically.Copyright