Viscoplastic Couette Flow in the Presence of Wall Slip with Non-Zero Slip Yield Stress

The steady-state Couette flow of a yield-stress material obeying the Bingham-plastic constitutive equation is analyzed assuming that slip occurs when the wall shear stress exceeds a threshold value, the slip (or sliding) yield stress. The case of Navier slip (zero slip yield stress) is studied first in order to facilitate the analysis and the discussion of the results. The different flow regimes that arise depending on the relative values of the yield stress and the slip yield stress are identified and the various critical angular velocities defining those regimes are determined. Analytical solutions for all the regimes are presented and the implications for this important rheometric flow are discussed.

Simultaneous Effects of Heat Transfer and Variable Viscosity on Peristaltic Transport of Casson Fluid Flow in an Inclined Porous Tube

The present study investigates the combined effects of varying viscosity and heat transfer on a Casson fluid through an inclined porous axisymmetric tube in the presence of slip effects. The modeled governing equations are solved analytically by considering the long wavelength and small Reynolds number approximations. The numerical integration is employed to obtain pressure rise and frictional force. A parametric analysis has been presented to study the effects of the Darcy number, angle of inclination, varying viscosity, velocity slip, thermal slip, yield stress, amplitude ratio, Prandtl number and Eckert number on the pressure rise, pressure gradient, streamlines, frictional force and temperature. The study reveals that an increase in the angle of inclination and viscosity parameter has a proportional increase in the pressure rise. Also, an increase in the porosity causes a significant reduction in the pressure rise.

Numerical Simulation of Newtonian Fluid Flow in a T-Channel with no Slip/Slip Boundary Conditions on a Solid Wall

The planar flow of a Newtonian incompressible fluid in a T-shaped channel is investigated. Three fluid interaction models with solid walls are considered: no slip boundary condition, Navier slip boundary condition and slip boundary condition with slip yield stress. The fluid flow is provided by uniform pressure profiles at the boundary sections of the channel. The problem is numerically solved using a finite difference method based on the SIMPLE procedure. Characteristic flow regimes have been found for the described models of liquid interaction with solid walls. The estimation of the influence of the Reynolds number, pressure applied to the boundary sections and the parameters of these models on the flow pattern was performed. The criterial dependences describing main characteristics of the flow under conditions of the present work have been demonstrated.