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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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Journal ArticleDOI
TL;DR: In this paper, a Searle-type magnetorheometer (essentially a concentric cylinder rotating in a cup) was designed and fabricated at the University of Maryland, and two commercial MREAs were characterized over the shear rate range of 0-25 000 s-1.
Abstract: Magnetorheological energy absorbers (MREAs) have been successfully deployed in occupant protection systems to protect against potentially injurious shock, crash and blast loads. These MREAs operate at shear rates upwards of 25 000 s-1, but magnetorheological fluids (MRFs) are typically characterized for shear rates up to 1000 s-1 in commercially available parallel counter-rotating disk rheometers. Because of the lack of availability of data at the required high shear rates, a Searle-type magnetorheometer (essentially a concentric cylinder rotating in a cup) was designed and fabricated at the University of Maryland. Using this magnetorheometer, two commercial MRFs were characterized over the shear rate range of 0-25 000 s-1 . It is shown that the rheometer was successful in replicating available characterization data at low shear rate, as well as quantifying high shear rate behavior as a function of applied field. In addition, it was shown that the Herschel-Bulkley constitutive model is appropriate and successfully characterized the apparent viscosity vs. shear rate behavior of the MRFs over this shear rate range. Experimental data demonstrate that an increase in field dependent yield stress can be realized over this entire shear rate range, so that MREAs can be designed using data taken with the magnetorheometer. Finally, the Mason number, which has been shown to be a useful non-dimensional number at low shear rates, also provides a useful physical interpretation at high shear rates.

24 citations

Journal ArticleDOI
TL;DR: In this paper, a two-fluid Rolie-poly approximation for entangled polymer solutions is studied and the authors show that the time to reach steady state becomes very long as the gap width increases.
Abstract: This paper continues our recent studies of the flow behavior of a two-fluid Rolie-Poly approximation for entangled polymer solutions. The model studied is similar to that used in our previous work, but now incorporates isotropic elastic contributions to the stress, as required for thermodynamic consistency. These contributions play no role in the dynamics of a single phase, incompressible polymer fluid. However, in the two-fluid model, each fluid phase, the polymer and the solvent, is compressible, and the isotropic elastic contribution to the stress cannot be neglected. We show that this change in the model leads to the prediction of a high Weissenberg number linear instability in simple shear flow, in addition to the linear instability at lower Weissenberg numbers that was identified in our preceding study. We then consider the dynamics of the full nonlinear system for both linear shear flow and the Taylor–Couette geometry. The linear shear flow solutions are used primarily to explore the details of the flow that develops from the high Weissenberg number instability. The Taylor–Couette geometry is studied for gap widths that are wide enough to allow detailed experimental measurements, and one primary focus is then to follow the transient evolution of the flow. We show that the time to reach steady state becomes very long as the gap width increases. However, the velocity and concentration distributions both show significant changes and banded structures for much smaller times, thus suggesting that the Taylor–Couette geometry is a practical system for experimental studies and can be directly compared with the present theory.

24 citations

Journal ArticleDOI
TL;DR: In this article, the steady boundary-layer flow of a non-Newtonian fluid over a moving wedge in a moving fluid is studied numerically for some values of the involved parameters, and the effects of these parameters on the skin friction coefficient are analyzed and discussed.
Abstract: The steady boundary-layer flow of a non-Newtonian fluid, represented by a power-law model, over a moving wedge in a moving fluid is studied in this paper. The transformed boundary-layer equation is solved numerically for some values of the involved parameters. The effects of these parameters on the skin friction coefficient are analyzed and discussed. It is found that multiple solutions exist when the wedge and the fluid move in the opposite directions, near the region of separation. It is also found that the drag force is reduced for dilatant fluids compared to pseudo-plastic fluids.

24 citations

Journal ArticleDOI
22 Nov 2013-PLOS ONE
TL;DR: The unsteady natural convection flow of an incompressible viscous fluid near a vertical plate that applies an arbitrary shear stress to the fluid is studied using the Laplace transform technique.
Abstract: The unsteady natural convection flow of an incompressible viscous fluid near a vertical plate that applies an arbitrary shear stress to the fluid is studied using the Laplace transform technique. The fluid flow is due to both the shear and the heating of the plate. Closed-form expressions for velocity and temperature are established under the usual Boussinesq approximation. For illustration purposes, two special cases are considered and the influence of pertinent parameters on the fluid motion is graphically underlined. The required time to reach the steady state in the case of oscillating shear stresses on the boundary is also determined.

24 citations

Journal ArticleDOI
TL;DR: In this paper, the yield stress and other rheological parameters of gum karaya suspensions were investigated with the main objective to determine the yield-stress and other parameters using various models.
Abstract: Rheological characteristics of gum karaya suspensions which is proposed as a fracturing fluid were investigated with the main objective to determine the yield stress and other rheological parameters using various models. The flow hysteresis confirms the thixotropic behavior of fluid with increased structural breakdown at higher concentration and temperature. An empirical model developed for the studied samples accurately predicts the temperature and polymer concentration sensitivity of the apparent viscosity. The Herschel-Bulkley model showed the best fit to the experimental data; however, the yield stress obtained from some of the samples using nonlinear regression (NL) method reported physically insignificant, negative values. The proposed optimization technique, i.e., “Particle Swarm Optimization” offered the most realistic results with faster convergence over genetic algorithm making it a better choice. The oscillatory study provided more reliable yield stress values and revealed the thermogelation behavior of polymer suspensions making it suitable for high-temperature fracturing application.

24 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202341
202295
202117
202022
201920
201836