Energy storage in drag-reducing polymer solutions

A new theory, which relates viscous drag reduction to the energy stored by polymer molecules subjected to a fluctuating wall shear rate, is proposed for the origin of the Toms effect. The strain energy densities of several polymer solutions were estimated from bead‐spring theory. The requisite molecular polymers were optimized by a least‐squares fit of calculated to observed intrinsic viscosities. Friction reduction was found to be a monotonic function of the strain energy density for a given polymer–solvent combination. The correlation was independent of molecular weight and concentration for pipes of 0.5–2.0 in. diameter. Differences between the points of onset of drag reduction for different polymer–solvent combinations may be due to the unequal effect of internal viscosity.