Dynamical behavior in the nonlinear rheology of surfactant solutions

Bandyopadhyay, Ranjini and Sood, AK (2000) Dynamical behavior in the nonlinear rheology of surfactant solutions. In: STATISTICAL PHYSICS: Third Tohwa University International Conference, 8-12 Nov 1999 , Location: Fukuoka (Japan) .

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Abstract

Several surfactant molecules self-assemble in solution to form long, flexible wormlike micelles which get entangled with each other, leading to viscoelastic gel phases. We discuss our recent work on the rheology of such a gel formed in the dilute aqueous solutions of a surfactant CTAT. In the linear rheology regime, the storage modulus G′(ω) and loss modulus G″(ω) have been measured over a wide frequency range. In the nonlinear regime, the shear stress σ shows a plateau as a function of the shear rate math above a certain cutoff shear rate mathc. Under controlled shear rate conditions in the plateau regime, the shear stress and the first normal stress difference show oscillatory time-dependence. The analysis of the measured time series of shear stress and normal stress has been done using several methods incorporating state space reconstruction by embedding of time delay vectors. The analysis shows the existence of a finite correlation dimension and a positive Lyapunov exponent, unambiguously implying that the dynamics of the observed mechanical instability can be described by that of a dynamical system with a strange attractor of dimension varying from 2.4 to 2.9.

Item Type:	Conference Paper
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	surfactants;nonlinear dynamical systems;viscoelasticity; rheology;shear strength;nonlinear differential equations; Lyapunov methods;time series;chaos
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	16 Mar 2012 10:17
Last Modified:	28 Mar 2012 06:00
URI:	http://eprints.iisc.ac.in/id/eprint/43887

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