Turbulence Structure and Mass Transport in a Channel Flow with Polymer Injection
Abstract
This study which examined a fully developed turbulent channel flow with polymer injection at the wall had two complimentary objectives. The first objective was to gain more understanding of the way in which long-chain, high- molecular-weight, water soluble polymers effect viscous drag reduction in turbulent wall flows. The second was to acquire information useful in the modeling of the transport processes in flows with polymer injection at the wall, particularly the high Schmidt number mixing process. A fluorescence technique was developed for time-resolved measurements of species concentration profiles. This technique was combined with laser velocimetry to obtain measurements of turbulent mass transport in a flow with polymer injection and, for comparison purposes, a flow with water injection. Two-component laser velocimeter measurements were made in both flows to examine the effect of both the injection process and the evolving polymer concentration field on the structure of turbulence. In the flows with injection, the major transport mechanism was identified as long (in the streamwise direction) filaments of high concentration fluid periodically lifting away from the near-wall region. When polymer was injected, mixing of the injected fluid with the outer flow required longer streamwise distance than for water injection. The high extensional viscosity of the polymer solution resulted in a strong correlation between large instantaneous polymer concentrations and small wall-normal velocity fluctuations causing lower levels of turbulent mass transport.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA202237
Entities
People
- David T. Walker
- William G. Tiederman
Organizations
- Purdue University