Pipe Flows of Dilute Aqueous Polymer Solution : Part 3, Viscous Sublayer and Adjacent Wall Region

概要

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Streamwise components of turbulent velocity, microscale and velocity spectra were measured using hot wire secnsors. The experiment suggests that by additives of polymer large eddy structures in an adjacent wall region are increased and that small scale eddies are reduced. The wall regions both of a Newtonian fluid and a dilute polymer solution are studied theoretically based on Townsend's method. The analysis shows; 1) the velocity profile in the wall layer is determined by applying energy equilibrium hypothesis to an attached eddy; 2) the Toms effect is explained by a pair structure of attached eddies and an elongational viscosity of polymer solution:3) the thickness of viscous sublayer of polymer solution is determined by concentration, intrinsic viscosity, number of monomer units, relaxation time and friction velocity; and 4) the pipe friction coefficient in the saturated region of the phenomenon is predicted without experiments.
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