  Drag reduction, or, what is the same, mean velocity increase in a turbulent
flow at a fixed pressure drop through the addition of tiny amounts (several
parts per million) of high molecular weight polymers (Thoms effect), is known
already for more than sixty years. Rather long ago it was understood that this
effect is related to supramolecular structures formed in the flow. Recent
experiments by S. Chu, E.S.G. Shaqfeh and their associates, where the motion of
supramolecular structures was directly observed, made it possible to understand
and quantify the dynamic interaction of the polymeric structures with the
solvent (water) flow. These results lead to the construction of a mathematical
model of the Thoms effect, based on the Kolmogorov(1942)-Prandtl(1945)
semi-empirical theory of shear flow turbulence.
