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.

Flow, thermal criticality and transition of a reactive third-grade fluid in a pipe with Reynolds' model viscosity

Abstract: Neglecting the consumption of the material, a steady incompressible flow of an exothermic reacting third-grade fluid with viscous heating in a circular cylindrical pipe is numerically studied for both cases of constant viscosity and Reynolds’ viscosity model. The coupled ordinary differential equations governing the flow in cylindrical coordinates, are transformed into dimensionless forms using appropriate transformations, and then solved numerically. Solutions using Maple are presented in tabular form and given in terms of dimensionless central fluid velocity and temperature, skin friction and heat transfer rate for three parametric values in the Reynolds’ case. The numerical results for the velocity and temperature fields are also presented through graphs. Bifurcations are discussed using shooting method. Comparisons are also made between the present results and those of previous work, and thus verify the validity of the provided numerical solutions. Important properties of thermal criticality are provided for variable viscosity parameter and reaction order. Further numerical results are presented in the form of tables and graphs for transition of physical parameters, while varying certain flow and fluid material parameters. Also, the flow behaviour of the reactive fluid of third-grade is compared with those of the Newtonian reactive fluid.

Tribological properties of dry, fluid, and boundary friction

Abstract: A friction pair is studied under lubricant-free dry friction, hydrodynamic, and boundary lubricant conditions. It is shown that, in dry friction, the number of harmonics in the time dependence of the coordinate of the lower rubbing block decreases with increasing frequency of an applied periodic action until the interacting surfaces stick when a critical frequency is exceeded. The surfaces then move together. The behavior of a friction pair with a lubricant made of a Newtonian fluid, pseudoplastic fluid, or dilatant non-Newtonian fluid is analyzed in the hydrodynamic case. It is found that a pseudoplastic fluid or a boundary lubricant leads a intermittent (stick-slip) friction mode, which is one of the main causes of fracture of rubbing parts, over a wide parametric range.

Free convection flows over a vertical plate that applies shear stress to a fractional viscous fluid

Abstract: Free convection flow of a fractional viscous fluid over an infinite vertical plate with exponential heating is studied using a fractional derivative with non-singular kernel. Fluid motion is induced by the plate that applies an arbitrary time-dependent shear stress to the fluid. Closed-form solutions for the dimensionless velocity and temperature fields and Nusselt number are established under the usual Boussinesq approximation. The obtained results can generate exact solutions for any motion with technical relevance of this type. Moreover, fluid’s velocity is presented as a sum of its mechanical and thermal components. A semi analytical solution based on the Stehfest’s formula for the inverse Laplace transform is also obtained. Finally, the influence of fractional parameter on the fluid motion as well as the contributions of mechanical and thermal components of velocity are graphically underlined and discussed.

On a Fluid-Structure Model in Which the Dynamics of the Structure Involves the Shear Stress Due to the Fluid

Abstract: In this paper we consider a model for fluid-structure interaction. The hybrid system describes the interaction between an incompressible fluid in a three-dimensional container with interior a fixed domain and a thin elastic plate, the interface, which coincides with a flexible flat part of the surface of the vessel containing the fluid. The motion of the fluid is described by the linearized Navier–Stokes equations and the deformation of the plate by the classical plate equations for in-plane motions, modified to include the viscous shear stress which the fluid exerts on the plate as well as damping of Kelvin–Voigt type. We establish the existence of a unique weak solution of the interactive system of partial differential equations by considering an appropriate variational formulation. Uniform stability of the energy associated with the model is shown under the assumption that the potential plate energy is dominated by the dissipation induced by the viscosity of the fluid. The retention of the physical parameters in the problem is an a priori requirement in this physical condition.