Parameters of Drag Reducing Polymers and Drag Reduction Performance in Single-Phase Water Flow

Drag Reduction by Surfactant Solutions in Gravity Driven Flow Systems

Efflux time measurements are carried out for gravity draining of a liquid from a large cylindrical tank (where the flow is essentially laminar) through single exit pipe in the absence and presence of Cetyl Pyridinium Chloride (CPC) surfactant solutions. The variables considered are initial height of liquid in the tank, dia. of tank, length of the exit pipe and concentration of surfactant. T...

Maximum drag reduction simulation using rodlike polymers.

Simulations of maximum drag reduction (MDR) in channel flow using constitutive equations for suspensions of noninteracting rods predict a few-fold larger turbulent kinetic energy than in experiments using rodlike polymers. These differences are attributed to the neglect of interactions between polymers in the simulations. Despite these inconsistencies the simulations correctly reproduce the ess...

Superposition of drag reduction due to riblets on drag reduction due to polymers

Drag reduction in the turbulent Kolmogorov flow.

We investigate the phenomenon of drag reduction in a viscoelastic fluid model of dilute polymer solutions. By means of direct numerical simulations of the three-dimensional turbulent Kolmogorov flow we show that drag reduction takes place above a critical Reynolds number Re(c). An explicit expression for the dependence of Re(c) on polymer elasticity and diffusivity is derived. The values of the...

Natural Drag-Reducing Polymers: Discovery, Characterization and Potential Clinical Applications

About seven decades ago, it was discovered that special long-chain soluble polymers added to fluid at nanomolar concentrations significantly reduce resistance to turbulent flow (Toms effect). These so-called drag-reducing polymers (DRPs) do not affect resistance to laminar flow. While the flow parameters associated with the Toms effect do not occur in the cardiovascular system, many later studi...