Accession Number:

AD0868160

Title:

Dilution in a Turbulent Boundary Layer with Polymeric Friction Reduction

Descriptive Note:

Corporate Author:

NAVAL UNDERSEA RESEARCH AND DEVELOPMENT CENTER SAN DIEGO CA

Personal Author(s):

Report Date:

1970-04-01

Pagination or Media Count:

36.0

Abstract:

The dilution by turbulent mixing of a polymer solution after injection into a turbulent boundary layer with polymeric friction reduction is considered. Two-dimensionality and constant-pressure flow over a flat plate are assumed. The intermittency of turbulence and scalar concentration, as well as the effects of friction-reduction on the mean velocity profile, are treated. The negative roughness analogy of polymeric friction reduction is invoked to justify the assumption that all significant properties of the outer-layer region satisfy the Newtonian-fluid outer-layer similarity laws, including those for velocity-defect, turbulence intermittency, and mean concentration in the final zone of mixing. This assumption is expected to be valid in cases of low polymer concentration and moderate wall shear stresses. Thus the polymer is treated like a passive scalar in the outer layer. A notable feature of the predicted mixing similarity law is that the mean concentration near the wall is underestimated by about 40 by the ordinary volume-flux average concentration in the boundary layer. A comparison with preliminary experimental results suggests that the predictions of far-downstream mixing are useful at least for low polymer concentrations and moderate wall shear stresses. The final-zone predictions are expected to be useful in estimating the obtainable friction reduction and boundary layer development on a slender body far downstream of a slot through which polymer solution is injected into the boundary layer.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE