Sisko Fluid Research Articles

On the Rayleigh problem for a Sisko fluid in a rotating frame

The unsteady rotating flow of a Sisko fluid bounded by a suddenly moved infinite flat plate is investigated. The fluid is electrically conducting in the presence of a transverse applied time-dependent magnetic field. A highly non-linear differential equation resulting from the balance of momentum and mass, coupled with appropriate boundary and initial conditions is solved numerically. The numerical solutions for different values of the parameters are compared and discussed.

Thin film flow of non-Newtonian fluids on a vertical moving belt using Homotopy Analysis Method

In this study, the problem of thin film flow of two non-Newtonian fluids namely, a Sisko fluid and an Oldroyd 6-constant fluid on a vertical moving belt that modeled by a system of nonlinear differential equations is studied. The system is solved using the Homotopy Analysis Method (HAM), which yields an analytic solution in the form of a rapidly convergent infinite series with easily computable terms. Homotopy analysis method contains the auxiliary parameter , which provides us with a simple way to adjust and control the convergence region of solution series. By suitable choice of the auxiliary parameter , reasonable solutions for large modulus can be obtained.

Magnetohydrodynamic flow of a Sisko fluid in annular pipe: A numerical study

AbstractThis paper presents a numerical study for the unsteady flow of a magnetohydrodynamic (MHD) Sisko fluid in annular pipe. The fluid is assumed to be electrically conducting in the presence of a uniform magnetic field. Based on the constitutive relationship of a Sisko fluid, the non‐linear equation governing the flow is first modelled and then numerically solved. The effects of the various parameters especially the power index n, the material parameter of the non‐Newtonian fluid b and the magnetic parameter B on the flow characteristics are explored numerically and presented through several graphs. Moreover, the shear‐thinning and shear‐thickening characteristics of the non‐Newtonian Sisko fluid are investigated and a comparison is also made with the Newtonian fluid. Copyright © 2009 John Wiley & Sons, Ltd.

Rayleigh problem for a MHD Sisko fluid

The problem of unsteady unidirectional flow of an incompressible Sisko fluid bounded by a suddenly moved plate is studied. The fluid is magnetohydrodynamic (MHD) in the presence of a time-dependent magnetic field applied transversely to the flow. The non-linear flow problem arising from the laws of momentum, mass and suitable boundary and initial conditions is solved analytically using Lie symmetry method. The manner in which the various emerging parameters affect the structure of the velocity is delineated.

Implicit differential equation arising in the steady flow of a Sisko fluid

Consideration is given to the thin film flow of a Sisko fluid on a moving belt. Using the implicit function theorem, an existence result for the solution of the resulting non-linear differential equation is established. Also, the homotopy analysis method is used to obtain approximate analytical solution of the problem for non-integer values of the power index. The numerical results thus obtained are presented graphically and the salient features of the solution are discussed for various values of the power index parameter. The results obtained reveal many interesting behaviors that warrant further study of the equations related to non-Newtonian fluid phenomena, especially the shear-thinning phenomena. Shear-thinning reduces the wall shear stress.

Reduction and Solutions for Magnetohydrodynamic Flow of a Sisko Fluid in a Porous Medium

Reduction and Solutions for Magnetohydrodynamic Flow of a Sisko Fluid in a Porous Medium

Magnetohydrodynamic peristaltic motion of a Sisko fluid in a symmetric or asymmetric channel

This paper presents a numerical study for the peristaltic flow characteristics of a Sisko fluid in a symmetric or asymmetric channel. The fluid is assumed to be electrically conducting in the presence of a uniform magnetic field. The mathematical formulation consisting of nonlinear governing equations and boundary conditions is first casted into a dimensionless form. The resulting equation for long wavelength and low Reynolds number assumptions is then numerically solved using an iterative method. The behaviors of the shear-thinning and shear-thickening non-Newtonian Sisko fluids are compared with those of the corresponding Newtonian fluid. Velocity distributions, pressure gradients, shear stresses as well as streamline pattern with respect to various material parameters and phase differences of the wall peristalsis are investigated. Some typical characteristics of peristaltic motion, e.g. pumping against a pressure rise and trapping phenomena etc. are observed from the numerical results and discussed.

Wire coating analysis by withdrawal from a bath of Sisko fluid

In this paper, the wire coating analysis by withdrawal from a bath of Sisko fluid is investigated. The relevant equations are first modelled and then solved by utilizing the homotopy analysis method (HAM). The convergence of the obtained series solution is carefully analyzed. The influence of the non-Newtonian parameter on the velocity, volume flow rate, radius of coated wire, shear stress at the surface of the wire and the force required to pull the wire is seen and discussed.

Analytic solution for flow of Sisko fluid through a porous medium

This paper presents the analytic solution for flow of a magnetohydrodynamic (MHD) Sisko fluid through a porous medium. The non-linear flow problem in a porous medium is formulated by introducing the modified Darcy’s law for Sisko fluid to discuss the flow in a porous medium. The analytic solutions are obtained using homotopy analysis method (HAM). The obtained analytic solutions are explicitly expressed by the recurrence relations and can give results for all the appropriate values of material parameters of the examined fluid. Moreover, the well-known solutions for a Newtonian fluid in non-porous and porous medium are the limiting cases of our solutions.

Thin film flow of non-Newtonian fluids on a moving belt

Abstract In this paper, the thin film flow of two non-Newtonian fluids namely, a Sisko fluid and an Oldroyd 6-constant fluid on a vertical moving belt is considered. The nonlinear equations governing the flow problems are formulated and analyzed, using homotopy perturbation method due to He. Explicit expressions for velocity field are obtained and graphically sketched. Volume flux and average velocity are also calculated.

Characterisation of thixotropy revisited

This paper re-examines the 'proof' of Cheng and Evans (1965) that the equilibrium flow curve of a thixotropic fluid has a positive slope, and shows that the slope can indeed be negative in parts. The implication of this on thixotropic behaviour in viscometers is described. Such thixotropic fluids can develop shear banding in wide-gap viscometers in common with many other materials, a brief survey of which is given. Additionally, the interrelationship of the Cross and Sisko fluids as models of thixotropy is examined, leading to the creation of a new class of thixotropic models.

Approximations to the drag force on a sphere moving slowly through either an Ostwald‐De Waele or a Sisko fluid

Approximations to the drag force on a sphere moving slowly through either an Ostwald‐De Waele or a Sisko fluid