1106 Evaluation of relaxation time at shear-induced structure state of wormlike micelles solutions

Rheological properties of mixtures of hydroxypropylmethyl cellulose (HPMC), a nonionic associative cellulose ether, and sodium dodecylsulfate (SDS), an anionic surfactant, were investigated by viscosity measurements performed at different shear rates (0.1-6000 s-1). HPMC/SDS mixtures containing different concentrations of SDS (CSDS=0.00-3.50 % w/w) and HPMC concentrations which corresponded to the overlap parameter c/c*=3, 6, and 12 were prepared. All HPMC/SDS mixtures were found to be shear-thinning when examined in a low-end-to mid-range of the applied shear rates. The degree of shear-thinning, n, and viscosity of the mixtures were influenced by composition of HPMC/SDS mixtures and HPMC-SDS complex formation. The changes in n ranged from values typical for highly shear thinning to almost perfectly Newtonian liquids, and were more pronounced as c/c* was increased from 3 to 6 and 12. A change in flow profile and a buildup of the first normal stress difference (N1) was observed in HPMC/SDS mixtures with c/c*=6 and 12 and CSDS 0.55-1.00 % and 0.55-2.50 %, respectively, when a critical shear rate, crit. was exceeded, suggesting that a shear-induced structure formation in the mixtures took place.

Download Full-text

Shear-Induced Structure and Velocity Fluctuations in Particulate Suspensions Probed by Ultrasonic Correlation Spectroscopy and Rheology

10.1063/1.1764199 ◽

2004 ◽

Cited By ~ 6

Author(s):

Anatoliy L. Strybulevych

Keyword(s):

Correlation Spectroscopy ◽

Velocity Fluctuations ◽

Particulate Suspensions ◽

Shear Induced Structure ◽

Induced Structure

Download Full-text

Modification of turbulence caused by cationic surfactant wormlike micellar structures in two-dimensional turbulent flow

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.1058 ◽

2021 ◽

Vol 933 ◽

Author(s):

Kengo Fukushima ◽

Haruki Kishi ◽

Hiroshi Suzuki ◽

Ruri Hidema

Keyword(s):

Turbulent Flow ◽

Surfactant Solution ◽

Turbulent Energy ◽

Molar Ratio ◽

Wormlike Micelles ◽

Two Dimensional ◽

Turbulence Statistics ◽

Image Velocimetry ◽

Set Up ◽

Induced Structure

An experimental study is performed to investigate the effects of the extensional rheological properties of drag-reducing wormlike micellar solutions on the vortex deformation and turbulence statistics in two-dimensional (2-D) turbulent flow. A self-standing 2-D turbulent flow was used as the experimental set-up, and the flow was observed through interference pattern monitoring and particle image velocimetry. Vortex shedding and turbulence statistics in the flow were affected by the formation of wormlike micelles and were enhanced by increasing the molar ratio of the counter-ion supplier to the surfactant, ξ, or by applying extensional stresses to the solution. In the 2-D turbulent flow, extensional and shear rates were applied to the fluids around a comb of equally spaced cylinders. This induced the formation of a structure made of wormlike micelles just behind the cylinder. The flow-induced structure influenced the velocity fields around the comb and the turbulence statistics. A characteristic increase in turbulent energy was observed, which decreased slowly downstream. The results implied that the characteristic modification of the 2-D turbulent flow of the drag-reducing surfactant solution was affected by the formation and slow relaxation of the flow-induced structure. The relaxation process of the flow-induced structure made of wormlike micelles was very different from that of the polymers.

Download Full-text