Rheological and mass transfer properties of non-Brownian fiber suspensions are affected by fiber characteristics, fiber interactions, and processing conditions. In this thesis we develop several simulation methods to study the dynamics of single fibers in simple shear flow, as well as the rheology and mass transfer of fiber suspensions. Isolated, rigid, neutrally-buoyant, non-Brownian, slightly curved, nonchiral fibers in simple shear flow of an incompressible Newtonian fluid at low Reynolds number can drift steadily in the gradient direction without external forces or torques. The average drift velocity and direction depend on the fiber aspect ratio, curvature and initial orientation. The drift results from the coupling of rotational and translational dynamics, and the combined effects of flipping, scooping, and spinning motions of the fiber. Irreversible fiber collisions in the suspensions cause shear-induced diffusion. The shear-induced self-diffusivity of dilute suspensions of fibers increases with increasing concentration and increasing static friction between contacts. The diffusivities in both the gradient and vorticity directions are larger for suspensions of curved fibers than for suspensions of straight fibers. For suspensions of curved fibers, significant enhancements in the diffusivity in the gradient direction are attributed to fiber drift in the gradient direction. The shear-induced self-diffusivity of concentrated suspensions of fibers increases with increasing concentration before fiber networks or flocs are formed, after which the diffusivity decreases with increasing concentration. The diffusivity increases with increasing fiber equilibrium bending angle, effective stiffness, coefficient of static friction, and rate of collisions. The specific viscosity of fiber suspensions increases with increasing fiber curvature, friction coefficient between mechanical contacts, and solids concentration. The specific viscosity increases linearly with concentration in the dilute regime, and increases with the cube of the concentration in the semi-dilute regime. Concentrated fiber suspensions are highly viscous, shear thinning, and exhibit significant yield stresses and normal stress differences. Yield stresses scale with volume concentration and fiber aspect ratio in the same way as that observed in experiments. The first normal stress difference increases linearly with shear rate. The shear-induced diffusivity increases linearly with the derivative of the particle contribution to stress for dilute suspensions with respective to concentration. This correlation between rheology and shear-induced diffusion makes it possible to predict diffusivity from easily measured rheological properties.

Progress in Heat and Mass Transfer, Volume 5: Heat and Mass Transfer in Rheologically Complex Fluids compiles selected papers presented at the International Seminar held in Herceg Novi, Yugoslavia on September 8-12, 1970. This book discusses the continuum foundation of rheology; transport phenomena in turbulent flow of rheologically complex fluids; and heat-transfer effects in flowing polymers. The thixotropic effects in viscoelastic media; non-equilibrium thermodynamics and rheology of viscoelastic fluids; and flow instability due to convective time changes of consistency are also elaborated. This publication also covers the prediction method for turbulent momentum and heat transfer in viscous non-Newtonian liquids; methods for determining thermal properties of anisotropic systems; and convection in ferromagnetic fluid due to magneto caloric effect. This volume is beneficial to students and researchers interested in the heat and mass transfer in rheologically complex fluids.

Understanding the behaviour of particles suspended in a fluid has many important applications across a range of fields, including engineering and geophysics. Comprising two main parts, this book begins with the well-developed theory of particles in viscous fluids, i.e. microhydrodynamics, particularly for single- and pair-body dynamics. Part II considers many-body dynamics, covering shear flows and sedimentation, bulk flow properties and collective phenomena. An interlude between the two parts provides the basic statistical techniques needed to employ the results of the first (microscopic) in the second (macroscopic). The authors introduce theoretical, mathematical concepts through concrete examples, making the material accessible to non-mathematicians. They also include some of the many open questions in the field to encourage further study. Consequently, this is an ideal introduction for students and researchers from other disciplines who are approaching suspension dynamics for the first time.

Proceedings of the International Symposium on Two-Phase Systems