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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 generalized Oldroyd-B model with the fractional calculus approach is used to obtain exact analytic solutions for the velocity and the stress fields in terms of the Fox H-function.
Abstract: In this paper, the generalized Oldroyd-B model with the fractional calculus approach is used. Exact analytic solutions for the velocity and the stress fields in term of the Fox H-function are obtained by using the discrete Laplace transform for two types of flows of a viscoelastic fluid, namely, (i) flow due to impulsive motion in the presence of a constant pressure gradient and (ii) flow induced by an impulsive pressure gradient. The influence of various parameters of interest on the velocity and shear stress has been shown and discussed through several graphs. Moreover, a comparison between Oldroyd-B and generalized Oldroyd-B fluids is also made.
27 citations
TL;DR: In this article, the applicability of three non-Newtonian constitutive models (power-law, Casson, and Herschel-Bulkley models) to the determination of blood viscosity and yield stress with a scanning capillary-tube rheometer was examined.
Abstract: We examine the applicability of three different non-Newtonian constitutive models (power-law, Casson, and Herschel-Bulkley models) to the determination of blood viscosity and yield stress with a scanning capillary-tube rheometer. For a Newtonian fluid (distilled water), all three models produced excellent viscosity results, and the measured values of the yield stress with each model were zero. For unadulterated human blood, the Casson and Herschel-Bulkley models produced much stronger shear-thinning viscosity results than the power-law model. The yield stress values for the human blood obtained with the Casson and Herschel-Bulkley models were 13.8 and 17.5 mPa, respectively. The two models showed a small discrepancy in the yield stress values, but with the current data analysis method for the scanning capillary-tube rheometer, the Casson model seemed to be more suitable in determining the yield stress of blood than the Herschel-Bulkley model.
27 citations
01 Jan 1998
TL;DR: In this article, the authors divide the flow into two regions: the region near the wall where the movement of flow is controlled by the frictional resistance, and the other region outside the above not affected by the friction and therefore assumed to be an ideal fluid flow.
Abstract: All fluids are viscous. In the case where the viscous effect is minimal, the flow can be treated as an ideal fluid; otherwise the fluid is treated as a viscous fluid. If the movement of fluid is not affected by its viscosity, it could be treated as the flow of ideal fluid and the viscosity term could be omitted. The flow around a solid, however, cannot be treated in such a manner because of viscous friction. Nevertheless, only this friction affects the very thin region near the wall. Prandtl identified this phenomenon and had the idea to divide the flow into two regions : the region near the wall where the movement of flow is controlled by the frictional resistance, and the other region outside the above not affected by the friction and therefore assumed to be an ideal fluid flow. The former is called the boundary layer and the latter the main flow.
27 citations
TL;DR: In this article, the boundary-layer equations are solved for the case of two-dimensional flow of a second-order viscoelastic fluid near a stagnation point, and it is shown that the effect of visco-elasticity is not only to increase the wall-shear stress but also to cause oscillations in the velocity profile.
Abstract: The boundary-layer equations are solved for the case of two-dimensional flow of a second-order viscoelastic fluid near a stagnation point. It is shown that the effect of viscoelasticity is not only to increase the wall-shear stress but also to cause oscillations in the velocity profile. It is further shown that the constitutive equation for the second-order viscoelastic fluid is not applicable to the analysis of stagnation point flow for Weissenberg numbers greater than approximately 0.32.
27 citations
TL;DR: In this article, the governing nonlinear equation for the unsteady flow of an incompressible fourth grade fluid is modelled and the fluid is also subjected to a magnetic field.
Abstract: The governing nonlinear equation for the unsteady flow of an incompressible fourth grade fluid is modelled. The fluid is also subjected to a magnetic field. In addition, we investigate steady flow between parallel plates with one plate at rest and the other moving parallel to it at constant speed with a suction velocity normal to the plates. Boundary conditions play a significant role. We construct the numerical solution to the sixth order nonlinear differential equation. It is found that the velocity increases with the increase in the material parameters of the fourth grade terms of the fluid.
27 citations