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.

On the non-orthogonal stagnation flow of the Oldroyd-B fluid

Abstract: This paper is concerned with a non-orthogonal stagnation flow of an Oldroyd-B fluid between two parallel plates. We reduce the problem to a set of ordinary differential equations (ODE's), which is then solved with finite differences using a parameter continuation method. Perturbation analyses are also carried out for small Reynolds numbers and small Weissenberg numbers respectively. The solution of the set of ODE's is discussed. It is known that for a Newtonian fluid, the stagnation point shifts from the potential flow case in the opposite direction of the tangential velocity. The effect of the fluid elasticity is to reduce this shift. It is also shown that the Oldroyd-B model has a limiting Weissenbeg number, depending on the angle of the injected flow.

Effect of hydrostatic pressure and temperature on rheological characteristics of alpha-lactalbumin.

Abstract: The flow behavior of pressure and temperature-treated α-lactalbumin dispersions was studied using a controlled rate rheometer. Dispersions 10% (w/w) of α-lactalbumin were subjected to high hydrostatic pressure from 100 MPa to 400 MPa at 20°C for 30 min or thermal treatment from 20°C to 80°C for 15 min at atmospheric pressure, followed by rheological characterisation at shear rates between O/s and 200/s. The shear stress-shear rate data of both pressure and heat-treated α-lactalbumin dispersions were described with the Herschel Bulkley model with yield stress. Dispersions exhibited shear-thinning behavior with flow behavior indices less than unity. Hydrostatic pressure treatment of α-lactalbumin samples did not change the magnitude of rheological parameters (p>0.05) and there was no gel formation. Consistency coefficient and apparent viscosity at 100/s decreased linearly with temperature and followed the Arrhenius relationship. The flow activation energy was found to be 10.18 kJ/mol and 11.57 kJ/mol for consistency index and apparent viscosity, respectively. Lower flow activation energy signified lesser molecular interaction or denaturation of protein molecules during thermal treatment of α-lactalbumin.

Flow of a simple non-newtonian fluid past a sphere

Abstract: Creeping flow past a sphere is solved for a limiting case of fluid behaviour: an abrupt change in viscosity.

Flow of an elastico-viscous fluid past an oscillating plate

Abstract: An exact solution for the flow of an elastico-viscous fluid (Walters' liquid B') due to an oscillating infinite plate has been derived. It has been observed that forgwt=0, (ω — frequency,t — time) the flow near the plate may become unstable with increasing ω whereas forωt>0, the velocity increases with increasingω. The shearing stress decreases with increasingω.

A Model of Averaged Molecular Viscosity for Turbulent Flow of Non-Newtonian Fluids

Abstract: A novel turbulence model for flows of viscoplastic fluid is presented. It is based on the Reynolds-Averaged approach. A closed model for the averaged viscosity that takes into account its nonlinear dependence on the fluctuating rate of deformation tensor is proposed. Test calculations were performed for power-law fluid and Herschel–Bulkley fluid flows in a straight round pipe. Numerical data obtained with the use of the proposed model are compared with the results of direct numerical simulations. The proposed model adequately describes the reduction in the turbulent transport of momentum with decreasing power-law index and with increasing yield stress of the fluid.