by P. H. Diamond*
 
 

It has long been known that addition of quite small concentrations of

polymer additives to turbulent pipe flows results in significant reductions

in drag. Previous theoretical approaches to explaining this phenomena have

invoked enhanced viscosity in the buffer layer due to polymer coil-stretch

transition (Lumley) or appealed to rather qualitative notions of enhanced

elasticity (DeGennes). A simple model, based on coupled equations for the

fluid velocity and (tensor) polymer elasticity field will be presented.

This model, which exhibits small scale elastodynamic waves, concretely

realizes DeGennes' qualitative notions in a system quite similar to

incompressible MHD. It is then easy to see drag reduction emerge as a

consequence of the competition between fluid and elastic stresses.

Scalings with concentration and polymer size will be discussed.
 
 

*Patrick H. Diamond

Professor of Physics

University of California, San Diego

Physics 0319, Urey Hall 7234

9500 Gilman Drive

La Jolla, CA 92093-0319

(858) 534-4025 office*

(858) 534-7697 fax*

pdiamond@physics.ucsd.edu
 
 

* Note new area code effective 6/12/99.