Drag reduction molecular parameters

The proposed mechanisms of models to explain the drag reduction phenomenon are based on either a molecular approach or fluid dynamical continuum considerations, but these models are mainly empirical or semi-empirical in nature. Models constructed from the equations of motion (or energy) and from the constitutive equations of the dilute polymer solutions are generally not suitable for use in engineering applications due to the difficulty of placing numerical values on all the parameters. In the absence of a more generally accurate model, semi-empirical ones remain the most useful for applications. 

It must, however, be borne in mind that a comparison such as that in Fig. 9 is incomplete, because nothing is known about the molecular parameters. As already stated in the summary, it is the aim of the present investigations to research the comparative influence of molecular parameters of polymers with respect to their effectiveness as drag reduction factors. The aforementioned molecular parameters include molecular... 

The aim of the work under consideration was to correlate the effectiveness of the drag reduction with the molecular parameters of the polymer causing it. 

The main interest of this work, therefore, lay in the field of water-soluble polymers and their influence on drag reduction in turbulent pipe flow, as it is from this field that the major technological use is to be expected. The investigation of the influential parameters for this class of polymers, such as molecular weight and distribution thereof, thermodynamic quality of the solvent, to name but a few (see Sect. 6.3.3), must precede a clear-cut characterization (see Sect. 6.3.1) of the polymer used. 

Hunston, D.L. Zakin, J.L. Effect of molecular parameters on the flow rate dependence of drag reduction and similar phenomena. In Progress in Astronautics and Aeronautics, Hough, S.R., Ed. American Institute of Aeronautics and Astronautics New York, 1980 Vol. 72, 373-385. 

McCormick, C. L., Hester, R. D., Morgan, S. E., and Safleddine, A. M., Water-soluble copolymers 31. Effects of molecular parameters, solvation, and polymer associations on drag reduction performance. Macromolecules, 23, 2132-2139 (1990). 

Wade, R. H., A Study of Molecular Parameters Influencing Polymer Drag Reduction, Naval Undersea Center, San Diego, CA, 1975. 

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