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.

A variational approach to non-steady non-Newtonian flow in a circular pipe

Abstract: The transient response of a non-Newtonian power-law fluid to several assumed forms of pressure pulse in a circular tube is analysed by the semi-direct variational method of Kanntovorich. Velocity profiles are shown for several power-law indices, and by comparing the results for the Newtonian case with the exact solution given by Szymanski, it is observed that the results are good to 5%. More accurate solutions have been found for the case involving Newtonian fluid flow. New results are reported concerning the effect of a triangular pressure pulse on the development and transient response of the flow field of a non-Newtonian fluid.

The model of seal mechanism for magnetic fluid and related experimental study

Abstract: Magnetic fluid is a kind of magneto-rheological fluid. In this paper, the mechanism of magnetic rheology effect was proposed and the yield stress formula of magneto-rheological fluid was derived, based on the dispersion and agglomeration theory of suspension liquid. In accordance with the magnetic rheology effect of magneto-rheological fluid, the computational formula of magnetic liquid seal pressure was concluded, with the seal pressure related to the yield stress of magnetic liquid and the length and clearance of leakproof structure. Using narrow gap magneto-rheological fluid rheology property test system, the yield stress of existing magnetic liquid was tested and an available seal device using magnetic liquid was studied, which proved that the calculation via formula proposed agreed well with the experimental results. DOI: http://dx.doi.org/10.5755/j01.mech.22.4.16156

Effect of Solid Particle Concentration on Drilling Fluid Rheological Behavior and its Impact on Pressure Losses

Abstract: Solid particles in suspension in a fluid, like barite, lost circulation material (LCM), cuttings or cavings, influence the pressure losses that are experienced when pumping or moving a drill-string in a borehole. As the volume fractions of those different solid particles varies along the hydraulic circuit, it is desirable to estimate the impact of local solid concentrations on pressure drops. The influence of solid particles on the rheological behavior of fluid has mostly been studied for Newtonian fluids, but very little experimental work has been published for non-Newtonian fluids like drilling muds. For that reason, a series of measurements, made with a scientific rheometer has been conducted on a typical KCl/Polymer water-based mud. The experimental investigation covers the effect of particle concentration on the rheological behavior of the mix, in conjunction with the particle size. The change of rheological behavior is slow at low solid concentrations but increases exponentially with larger proportions of solid in suspension. Furthermore, the increase of effective viscosity is larger with fine particles than with coarser ones. Empirical formulas are proposed to describe how the original Herschel-Bulkley rheological behavior of a base fluid can be modified to incorporate the effects of the variation of solid concentrations in the fluid mix. All these results are based on measurements made with a scientific rheometer. As computerized and high precision rheometers are usually not available at the rig site, we describe a methodology to utilize standard model 35 rheometer measurements to estimate the pressure loss gradient as a function of the volumetric solid content.

The dynamics of a simple model for a thixotropic yield stress fluid

Abstract: We study the dynamics of a model for thixotropic yield stress fluids which was recently proposed in [1] . This is based on the partially extended convected model (PEC), modified to allow for a non-zero shear stress limit for large shear rates (PECR), and combined with a Newtonian solvent to enable yielding to homogeneous shear flow (PECR-N) under a prescribed shear stress. We define ϵ to be the ratio of retardation time to relaxation time and focus on the limit ϵ → 0. Multiple time scales arise and the solutions are investigated with perturbation methods, in conjunction with direct computation of the full set of equations. Both PEC-N and PECR-N capture the experimentally observed phenomenon that the value of yield stress depends on the observation time. For the PECR-N model, we find transient solutions that are not expected from prior work on the PEC-N model, such as blow-up in finite time on the slow manifold, and yielded time-periodic flow.

Theory of the nonequilibrium structure of dense simple fluids. II. High-shear-rate effects

Abstract: The integral equation for the dynamic pair correlation function derived previously from the modified moment method is solved for a non-Newtonian soft-sphere fluid undergoing a plane Couette flow. In this approach, the dynamic pair correlation function is a functional of the shear stress, which determines the macroscopic state of the nonequilibrium fluid. The distortions of the structure factor at high shear rates are examined for a non-Newtonian fluid. Normal stress effects are included in the study presented. It is found that as the shear rate increases, the structure factor fractures into domains of high intensity in the xy (shear), xy, and yz planes in the wave-vector space