Drag reduction and turbulence modification in rigid particle suspensions

Abstract

Abstract Turbulent drag reductions on the order of 50% were obtained for pipe flow of submicron, rod‐like particle suspensions at weight concentrations of less than 0.5%. Wall Reynolds numbers as high as 40,000 were obtained for the suspensions. The suspended particle configuration was rigid and non‐elastic and was not affected by local strain rate fields. Longitudinal turbulence data are presented for two suspensions and for the Newtonian solvent at an average flow velocity of about 7 fps. Distinctly modified turbulence generation and dissipation were observed. The suspension exhibited smooth transitional flow behavior and increases in both macroscale and microscale. A particle length effect, or relaxation time effect, was observed with the larger relaxation time suspension exhibiting the more extreme flow and turbulence differences.