Review of chaos in the dynamics and rheology of suspensions of orientable particles in simple shear flow subject to an external periodic force

Asokan, K and Anil Kumar , CV and Dasan, J and Radhakrishnan, K and Satheesh Kumar, K and Ramamohan, TR (2005) Review of chaos in the dynamics and rheology of suspensions of orientable particles in simple shear flow subject to an external periodic force. Journal of Non-Newtonian Fluid Mechanics, 129. pp. 128-142.

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We review results obtained over a period of about a decade on a class of technologically and fundamentally important problems in suspension rheology viz., thermodynamics and rheology of dipolar suspensions of orientable particles in simple shearow. We also attempt to put our results into context with respect to recent work on rheochaos. The areas explored in this review include effects such as the fluid flow field, external forcing, Brownian discussion, Hydrodynamic interactions and their impact on the rheological properties of the suspension. The main feature of the presentation is the use of a uniform framework in which one or more of the above effects can be studied, based on Langevin type equations for particle orientations combined with a brute-force technique for computing orientational averages. These models are capable of capturing dynamical behavior in the system such as the presence of subharmonics or chaos, both in the dynamics and rheology, which current models based on Fokker-Planck type equations cannot. The tools developed allow for investigating how chaos in the system is accepted by Brownian discussion and hydrodynamic interactions. The presence of chaos opens up a number of novel possibilities for dynamical and rheological behavior of the system, which can be put to efficient use in many ways, eg. in separating particles by aspect ratio and in developing computer controlled intelligent rheology. The results also have implicationsfor certain areas of chaos theory, such as a new intermittency route to chaos and the possibility of non-trivial collective behavior in spatially extended systems. These studies highlight certain de�deficiencies in current techniques in the literature for handling the rheology of dilute and semi-dilute suspensions. In the presence of Brownian motion the proposed method computes the averages by simulating a set of deterministic equations rather than stochastic equations, leading to significant improvements in computational efficiency. This technique can be used to compute the orientation averages in certain parameter regimes where usual methods render the problem difficult to handle. The systems considered may also serve as a paradigm for analysing how microscopic chaotic fluctuation in spatially extended systems affect macroscopic averages.

Item Type: Article
Subjects: ENGINEERING > Fluid Mechanics and Thermodynamics
Depositing User: Dr. TR Ramamohan
Date Deposited: 06 Aug 2010 11:03
Last Modified: 07 May 2012 05:54

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