Accession Number : AD0660883

Title :   THE DAMPING OF TURBULENT FLOW BY LONG-CHAIN MOLECULES,

Corporate Author : NORTH AMERICAN ROCKWELL CORP ANAHEIM OCEAN SYSTEMS OPERATIONS

Personal Author(s) : VAN Driest,E. R.

Report Date : SEP 1967

Pagination or Media Count : 25

Abstract : The paper develops the fundamental idea that velocity fluctuations in turbulent flow near a wall are damped by viscous interaction with a grid of long-chain molecules, thus attenuating the Reynolds stresses and thereby reducing drag. Formulas are derived which relate pipe friction factor with Reynolds number, additive concentration, and a length which is characteristic of the particular additive used. The theory accounts for the essential features of experimental data on velocity profile and friction drag obtained by Elata, Lehrer, and Kahanovitz for guar gum and Ernst for carboxymethylcellulose. The analysis also admits turbulence reduction not only by macromolecules in solution, but also by foreign matter in mixture so long as they move with, or are entrained by, the fluid. (Author)

Descriptors :   (*TURBULENCE, DAMPING), (*POLYMERS, *LUBRICANTS), (*DRAG, REDUCTION), ADDITIVES, SKIN FRICTION, PIPES, CARBOXYMETHYLCELLULOSE, ATTENUATION, MATHEMATICAL ANALYSIS, FLUID FLOW

Subject Categories : Lubricants and Hydraulic Fluids
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE