Drag reduction and solvation in polymer solutions
نویسندگان
چکیده
A model is described which explains drag reduction (DR) in dilute polymer solutions in terms of solvation of macromolecular chains and formation of relatively stable domains. The domains partly suppress the vortex formation, act as energy sinks, and also play a role in mechanical degradation in flow (MDF). We report ultrasonically determined solvation numbers for a series of copolymers with the same chemical structure but differing widely in their intrinsic viscosities. The solvation numbers confirm the model. Thus, we have a criterion for selection of DR agents with low MDF for: oil well operations; crude oil transport; fire fighting; high sewer throughput; irrigation; hydrotransport of solids; marine applications; and biomedical applications including the arteriosclerosis prevention.
منابع مشابه
Drag Reduction in Turbulent Flow of Polymer Solutions
Progress in understanding turbulent drag reduction by polymer additives has recently been made on several fronts. The near-wall dynamics of Newtonian turbulence is becoming better understood. Detailed computations of complex flows of model polymer solutions are now possible. Insights into the effects of viscoelasticity have been gained from a number of important model flows, and the understandi...
متن کاملTurbulent Drag Reduction of polyelectrolyte solutions: relation with the elongational viscosity
We report measurements of turbulent drag reduction of two different polyelectrolyte solutions: DNA and hydrolyzed Polyacrylamide. Changing the salt concentration in the solutions allows us to change the flexibility of the polymer chains. For both polymers the amount of drag reduction was found to increase with the flexibility. Rheological studies reveal that the elongational viscosity of the so...
متن کاملPolymer flexibility and turbulent drag reduction.
Polymer-induced drag reduction is the phenomenon by which the friction factor of a turbulent flow is reduced by the addition of small amounts of high-molecular-weight linear polymers, which conformation in solution at rest can vary between randomly coiled and rodlike. It is well known that drag reduction is positively correlated to viscous stresses, which are generated by extended polymers. Rod...
متن کاملDrag 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...
متن کاملDrag Reduction by Anionic Surfactant Solutions in Gravity Driven Flow System
This paper presents efflux time experiments performed in the absence and presence of aqueous solutions of Drag Reducing Agents (DRAs) when a liquid is emptied from a large open cylindrical storage tank through an exit piping system. The drag reducing agents studied are Dodecyl benzene sulfonate anionic surfactant and a mixed solution of surfactant and sodium chloride counter ion. The variab...
متن کامل