Convex Curvature Effect on the Wake Including Recovery from the Curvature

Abstract

Streamwise convex-curvature effect including recovery process is discussed. Previous studies have demonstrated that even mild streamwise curvature has a marked effect on turbulence structure, heat transfer and skin friction coefficient. This effect is further investigated in the present study with Coles wake law. Coles previously reported that flows in or near equilibrium have a constant wake parameter depending on the strength of streamwise pressure gradient. Turbulent boundary layers on the curved and following recovery wall may not be in or near equilibrium and the wake parameter may depend upon the strength of curvature, δ/R. Different streamwise curvature strength, ranging 0.01–0.1, is tested to confirm the validity of the wake law. The ratio of wake parameter between the curved and flat wall is found to be proportional to that of skin friction coefficient for the flows in both convexly curved and recovery sections. This relationship describes the deviation of wake behavior from the flat-plate turbulent boundary layer due to convex curvature.