Grid Turbulence in Dilute High-Polymer Solutions 



15. Zimm, B.H., "Dynamics of Polymer Molecules in Dilute Solution Visco- 

 elasticity, Flow Birefringence and Dielectric Loss," J. Chem. Phys. 

 24:269-278 (1956) 



16. Tschoegl, N.W., "Influence of Hydrodynamic Interaction on the Viscoelastic 

 Behavior of Dilute Polymer Solutions in Good Solvents," J. Chem. Phys. 

 40:473-479 (1964) 



17. Corrsin, S., "Turbulence: Experimental Methods," Handbuch der Physik, 

 Vol. 8, edited by S. Flugge and C.A. Truesdell, Springer -Ver lag, Berlin, 

 1963, pp. 524-590 



18. Patterson, G.K., Hershey, H.C., Green, CD., and Zakin, J.L., "Effect of 

 Degradation by Pumping on Normal Stresses in Polyisobutyline Solutions," 

 unpublished 



DISCUSSION 



G. E. Gadd 



National Physical Laboratory 

 Felt ham, Middlesex, England 



Dr. Fabula's suggested explanation of "raggedness," that it might be due to 

 molecular clusters stretched out into long fibers, could also perhaps be relevant 

 to the following phenomena: 



1. In experiments* on eddy shedding behind a small circular cylinder, 

 Polyox in concentrations greater than 20 ppm had been found to halve the fre- 

 quency, whereas below 10 ppm it had no effect. 



2. Similarly, when Polyox solutions of greater than 20 ppm were poured, 

 they showed "stringiness," the formation of long hairlike filaments, which did 

 not seem to occur for less than 10 ppm concentration. 



3. Further, a laminar jet of coloured Polyox solution of greater than 20 

 ppm concentration emerging into uncoloured Polyox solution showed, when it 

 turned turbulent, a quite different kind of turbulence than for the similar flow of 

 water, with a complete suppression of the small eddies. No such eddy suppres- 

 sion occurred, however, below 10 ppm concentration, as White of Hendon had 

 showed, even though these weaker solutions are still very effective^ in reducing 

 turbulent drag. 



*G.E. Gadd, Nature 211:169 (1966). 



tj.W. Hoyt and A.G. Fabula, "The Effect of Additives on Fluid Friction," pp. 



947-974 in "Fifth Symposium on Naval Hydrodynamics: Ship Motions and Drag 



Reduction," ONR Report ACR- 1 1 2, 1964. 



71 



