Effects of Distributed Injection of Polymer Solutions on Turbulent Diffusion

Abstract

Abstract : Part of an extensive experimental investigation of the mechanics of turbulent diffusion is described for uniformly distributed injection of a polymer solution through a porous wall adjacent to a fully-developed turbulent pipe flow of water. The diffusion data were obtained over an active porous wall section and throughout the region immediately downstream of the porous wall. The previously recorded wall friction anomalies recorded in the region of distributed polymer injection are shown to depend on the viscosity of the resulting polymer solutions near the wall associated with reduced diffusion. Empirical diffusion coefficients give a quantitative determination of the effect of the polymer in reducing turbulent diffusion for the present case. The transitional sublayer was identified from these data as the boundary layer region requiring polymer to effect wall friction reduction. (Author)