Herschel–Bulkley fluid

About: Herschel–Bulkley fluid is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 49318 citations.

Rotating flow of Oldroyd-B fluid over stretchable surface with Cattaneo – Christov heat flux: Analytic solutions

Abstract: Purpose The purpose of this paper is to analyze the heat transfer effects on the stretched flow of Oldroyd-B fluid in a rotating frame. Cattaneo–Christov heat conduction model is considered, which accounts for the influence of thermal relaxation time. Design/methodology/approach Based on scale analysis, the usual boundary layer approximations are used to simplify the governing equations. The equations so formed have been reduced to self-similar forms by similarity transformations. A powerful analytic approach, namely, homotopy analysis method (HAM), has been applied to present uniformly convergent solutions for velocity and temperature profiles. Findings Suitable values of the so-called auxiliary parameter in HAM are obtained by plotting h-curves. The results show that boundary layer thickness has an inverse relation with fluid relaxation time. The rotation parameter gives resistance to the momentum transport and enhances fluid temperature. Thermal boundary layer becomes thinner when larger values of thermal relaxation time are chosen. Originality/value To the authors’ knowledge, this is the first attempt to study the three-dimensional rotating flow and heat transfer of Oldroyd-B fluid.

Explicit equations for laminar flow of herschel–bulkley fluids

Abstract: There are three typical problems encountered in pipe flows: unknown friction factor, unknown flow rate, and unknown diameter problems. A major problem in determining the solution to these flow problems occurs due to the implicit nature of the Darcy–Weisbach friction factor. Though explicit equations for flow of Newtonian fluids and Power Law fluids are available, no such usable equations exist for Herschel–Bulkley fluids. In this paper, explicit equations have been given for flow of Herschel–Bulkley fluids in the laminar regime.

An experimental investigation of the flow of an electro-rheological fluid in a Rayleigh step bearing

Abstract: The transport properties of unexcited and excited electro-rheological (ER) fluid in combined Couette and Poiseuille flow are investigated. In particular the question of whether the fluid can be considered as a continuum with Bingham plastic constitutive properties, even though it is a two-phase solid-liquid mixture, is addressed. The hydrodynamic pressures generated using ER fluid in a Rayleigh step bearing at the limiting condition of zero net flow rate were measured. The properties exhibited by the fluid are compared with independently obtained data showing the continuum principle to be applicable to the flows examined.

Dynamic Shear Flow Behavior of Magneto-Rheological Fluid between Two Rotating Parallel Disks under Relatively Weak Magnetic Field

Abstract: The transient shear stress variation and the flow patterns of an MR fluid have been investigated simultaneously under constant shear rate and relatively weak magnetic field using a parallel disk rotary rheometer. The effects of magnetic field, shear rate and gap height on the induced shear stress and the flow behavior of the MR fluid were evaluated. The behavior of shear stress changes remarkably and various flow patterns (cracks in packed MR fluid structure, grain-like particle’s agglomeration, line of grains, etc.) with MR fluid leakage out of the gap can be observed, depending on these parameters. The amount of the MR fluid leakage due to the centrifugal force also depends on these parameters. Both the evolution of pattern and the leakage of MR fluid might be responsible for the transient variation of shear stress.

Profile blunting and flow blockage in a yield stress fluid: A molecular dynamics study

Abstract: The flow of a simple glass forming system (a 80:20 binary Lennard-Jones mixture) through a planar channel is studied via molecular dynamics simulations. The flow is driven by an external body force similar to gravity. Previous studies show that the model exhibits both a static [F. Varnik et al., J. Chem. Phys. 120, 2788 (2004)] and a dynamic [F. Varnik and O. Henrich, Phys. Rev. B 73, 174209 (2006)] yield stress in the glassy phase. These observations are corroborated by the present work, where we investigate how the presence of a yield stress may affect the system behavior in a Poiseuille-type flow geometry. In particular, we observe a blunted velocity profile across the channel: A relatively wide region in the channel center flows with a constant velocity (zero shear rate) followed by a nonlinear change of the shear rate as the walls are approached. The observed velocity gradients are compared to those obtained from the knowledge of the shear stress across the channel and the flow curves (stress versus shear rate), the latter being determined in our previous simulations of homogeneous shear flow. Furthermore, using the value of the (dynamic) yield stress known from previous simulations, we estimate the threshold body force for a complete arrest of the flow. Indeed, a blockage is observed as the imposed force falls below this threshold value. Small but finite shear rates are observed at stresses above the dynamic but below the static yield stress. We discuss the possible role of the stick-slip-like motion for this observation.