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.

3D flow of a generalized Oldroyd-B fluid induced by a constant pressure gradient between two side walls perpendicular to a plate

Abstract: This paper deals with the 3D flow of a generalized Oldroyd-B fluid due to a constant pressure gradient between two side walls perpendicular to a plate. The fractional calculus approach is used to establish the constitutive relationship of the non-Newtonian fluid model. Exact analytic solutions for the velocity and stress fields, in terms of the Fox H-function, are established by means of the finite Fourier sine transform and the Laplace transform. Solutions similar to those for ordinary Oldroyd-B fluid as well as those for Maxwell and second-grade fluids are also obtained as limiting cases of the results presented. Furthermore, 3D figures for velocity and shear stress fields are presented for the first time for certain values of the parameters, and the associated transport characteristics are analyzed and discussed.

Laminar impinging jet heat transfer with a purely viscous inelastic fluid

Abstract: Laminar impinging flow heat transfer is considered with a purely viscous inelastic fluid. The rheology of the fluid is modeled using a strain rate dependent viscosity coupled with asymptotic Newtonian behavior in the zero shear limit. The velocity and temperature fields are computed numerically for a confined laminar axisymmetric impinging flow. Important features of the non-Newtonian developing flow field are described and contrasted with the Newtonian situation. It is demonstrated that very small departures from Newtonian rheology lead to qualitative changes in the Nusselt number distribution along the impinging surface. In particular, a mildly shear thinning fluid displays a pronounced off-stagnation point heat transfer maxima, a feature that is not observed with a Newtonian fluid. Hence, Newtonian fluid approximations cannot adequately describe experimental heat transfer measurements in such situations even though they may be deemed acceptable in terms of describing the velocity field in the incoming ...

Magnetohydrodynamic transient flows of a non-Newtonian fluid

Abstract: Some exact solutions of the time-dependent partial differential equations are discussed for flows of an Oldroyd-B fluid. The fluid is electrically conducting and incompressible. The flows are generated by the impulsive motion of a boundary or by application of a constant pressure gradient. The method of Laplace transform is applied to obtain exact solutions. It is observed from the analysis that the governing differential equation for steady flow in an Oldroyd-B fluid is identical to that of the viscous fluid. Several results of interest are obtained as special cases of the presented analysis.

Wicking with a yield stress fluid.

Abstract: This work presents an experimental investigation of the flow of a model yield stress fluid (yield stresses between 5 and 21 Pa) driven by capillarity in horizontal glass tubes with diameters ranging from 0.46 to 1.5 mm. It is shown that the liquid penetration stops after typically a few centimeters. The results disagree with a simple model based on the balance between capillary and frictional forces, suggesting that the yield stress fluid constitutive equation may not be valid in the immediate vicinity of the wall. Scaling is proposed with respect to a dimensionless number comparing the yield stress with the capillary pressure.

Nonlinear stability of a visco-plastically lubricated viscoelastic fluid flow

Abstract: A core-annular flow of an Oldroyd-B fluid surrounded by a lubricating Bingham fluid is studied using energy stability methods. We consider base flows for which the lubricating fluid is unyielded close to the interface. For small finite restrictions on the size of shear stress and elastic stress perturbations we are able to demonstrate the exponential decay of a suitable energy functional for sufficiently small Reynolds number and Weissenberg number. These results extend those of [1] where only inelastic fluids were considered.