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

IR@C-MMACS: CSIR-Centre for Mathematical Modelling and Computer Simulation, Bangalore

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Title Review of chaos in the dynamics and rheology of suspensions of orientable particles in simple shear ow subject to an external periodic force
 
Creator T R, Ramamohan
 
Subject Computational Fluid dynamics
 
Description We review results obtained over a period of about a decade on a class of technologically and fundamentally important problems in suspension rheology viz., the dynamics and rheology of dipolar suspensions of orientable particles in simple shear ow. We also attempt to put our results into context with respect to recent work Preprint submitted to Journal of Non-Newtonian Fluid mechanics3 September 2004 on rheochaos. The areas explored in this review include e�ects such as the uid ow �eld, external forcing, Brownian di�usion, 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 e�ects 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 behaviour 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 a�ected by Brownian di�usion and hydrodynamic interactions. The presence of chaos opens up a number of novel possibilities for dynamical and rheological behaviour of the system, which can be put to effcient use in many ways, eg. in separating particles by aspect ratio and in developing computer controlled intelligent rheology. The results also have implications for certain areas of chaos theory, such as a new intermittency route to chaos and the possibility of non-trivial collective behaviour in spatially extended systems. These studies highlight certain 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 signi�ficant 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 fluctuations in spatially extended systems a�ffect macroscopic averages.
 
Publisher CSIR Centre for Mathematical Modelling and Computer Simulation
 
Date 2004-09-03
 
Type Monograph
NonPeerReviewed
 
Format application/pdf
 
Identifier http://cir.cmmacs.ernet.in/197/1/rrcm0405abs.pdf
T R, Ramamohan (2004) Review of chaos in the dynamics and rheology of suspensions of orientable particles in simple shear ow subject to an external periodic force. Technical Report. CSIR Centre for Mathematical Modelling and Computer Simulation, C-MMACS,Bangalore 560037,India. (Unpublished)
 
Relation http://cir.cmmacs.ernet.in/197/