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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.
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TL;DR: In this article, the effect of the governing parameters, namely, heat source/sink, vortex viscosity, and buoyancy ratio on the velocity, microrotation velocity, and temperature has been discussed.
Abstract: UDC 536.25 The problem of fully developed mixed convection for a laminar flow of a micropolar fluid mixture in a vertical channel with a heat source/sink has been investigated. The plates exchange heat with an external fluid, and both conditions of equal and different reference temperatures of the external fluid are considered. The effect of the governing parameters, namely, heat source/sink, vortex viscosity, and buoyancy ratio on the velocity, microrotation velocity, and temperature has been discussed. An increase in the vortex viscosity parameter enhances microrotation and thus decreases the fluid velocity. The volume flow rate, total heat flux, and heat and species fluxes are shown to be lower than those for a Newtonian fluid in both the cases of heat absorption and generation.
12 citations
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TL;DR: In this article, an experimental and theoretical determination of the rheological performance of an electrorheological (ER) fluid when subjected to time-dependent applied loads is presented.
Abstract: This paper is concerned with an experimental and theoretical determination of the rheological performance of an electrorheological (ER) fluid when subjected to time-dependent applied loads. The experimental facility was built as a squeeze cell in which the fluid is sandwiched between two electrodes, one fixed and the other moving, which permits the instantaneous measurement of the mechanical and electrical responses of the fluid. The transient rheological characteristics of the fluid were assessed for various mechanical force levels and for constant voltage excitation of the fluid. Input and output stress levels across the fluid were monitored enabling the dynamic response of the fluid to be determined using a combination of displacement, force, velocity and acceleration transducers. The experimental results were compared with the results from a modified theoretical analysis, which employs a bi-viscous shear stress/shear strain characteristic of the electrically stressed fluid together with a fluid yield stress, which has a strain-direction dependence on the electric field.
12 citations
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TL;DR: In this article, the influence of viscoplastic rheological features on Rayleigh-Benard convection was investigated by numerical means in order to compare with first experimental results given by Darbouli et al. The fluid is modeled by a regularized Herschel-Bulkley law which is often used to fit numerous pasty fluids.
Abstract: The influence of viscoplastic rheological features on the Rayleigh-Benard convection is investigated by numerical means in order to compare with first experimental results given by Darbouli et al. The fluid is modeled by a regularized Herschel-Bulkley law which is often used to fit numerous pasty fluids. Natural convection in a two-dimensional square cavity heated from below is considered. Critical values of Oldroyd number Od and yield number Y are provided. Numerical results highlight a stabilizing effect of the yield stress as well as a destabilizing effect of increasing shear-thinning coefficient n as the increase in n enhances the heat transfer in the range of our calculations. Unyielded regions are located in the square corners of the cavity and in the cavity where convection occurs. The unyielded zones size increases with the increase in Od and can invade all the cavity for sufficiently large values of Od.
12 citations
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TL;DR: Two different forms for the wall shear stress vector from which AWSS and OSI are computed are studied, commonly used as a generalization from the two-dimensional setting, the latter is derived from the full decomposition of the wall traction force given by the Cauchy stress tensor.
Abstract: Hemodynamic indicators such as the averaged wall shear stress (AWSS) and the oscillatory shear index (OSI) are well established to characterize areas of arterial walls with respect to the formation and progression of aneurysms. Here, we study two different forms for the wall shear stress vector from which AWSS and OSI are computed. One is commonly used as a generalization from the two-dimensional setting, the latter is derived from the full decomposition of the wall traction force given by the Cauchy stress tensor. We compare the influence of both approaches on hemodynamic indicators by numerical simulations under different computational settings. Namely, different (real and artificial) vessel geometries, and the influence of a physiological periodic inflow profile. The blood is modeled either as a Newtonian fluid or as a generalized Newtonian fluid with a shear rate dependent viscosity. Numerical results are obtained by using a stabilized finite element method. We observe profound differences in hemodynamic indicators computed by these two approaches, mainly at critical areas of the arterial wall.
12 citations
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TL;DR: In this paper, the influence of the fluid behaviour index n, shear-dependent nonlinear viscosity k and the yield stress o H in blood flow through a stenosed artery was investigated by a joint effort of analytical and numerical techniques.
Abstract: In this paper, one-dimensional Herschel-Bulkley fluid flow through a stenosed artery, has been studied. The problem is investigated by a joint effort of analytical and numerical techniques. Analytical expressions for several flow variables are obtained. This model has been used to study the influence of the fluid behaviour index n, shear-dependent non-linear viscosity k and the yield stress o H in blood flow through a stenosed artery. The variations of axial and plug velocities, flow rate, wall shear stress and pressure gradient with n, k and o H, have been shown graphically. It is observed that axial velocity and flow rate increase with slip but decrease with yield stress and, wall shear stress increases in Herschel-Bulkley fluid in comparison with corresponding Newtonian fluid. Biorheological implications of the present modelling for some arterial diseases, are included in brief.
12 citations