Numerical simulation of drag reduction for turbulent flow in cylindrical annuli with axial corrugations

Abstract

A computational fluid dynamics study has been undertaken to determine the effect of axial corrugations on the inner and outer surfaces of cylindrical annuli in the turbulent flow regime. Results show that axial corrugations on either one or both surfaces has the potential to reduce drag for certain types of corrugations. Overall, it is found that drag reduction is increased with larger amplitude and longer wavelength corrugations. Corrugations on the inner and outer cylinders have similar effect to one another and can be combined on both surfaces for greater drag reduction than the sum of the individual effects. If corrugations are present on both surfaces, an out-of-phase arrangement is shown to yield the best drag reduction. An eccentric alignment of the inner cylinder is also shown to increase potential for drag reduction for the parameters considered in this study. Within the turbulent flow regime, it is shown that the Reynolds number has a weak effect on the potential drag reduction. For the geometries considered in this study, the drag reduction potential is up to approximately 25%.