Effect of chemical reaction in a third grade fluid in porous medium analyzed by unsteady magnetohydrodynamic couette

An analysis was carried out on unsteady magnetohydrodynamic (MHD) Couette third grade fluid in a porous medium in the presence of chemical reaction parameter. The Darcy’s law and Fick’s law of diffusion were introduced to stimulate the porosity and chemical reaction in the problem. The resulting flow problem was investigated and model of the problem in form of partial differential equations were obtained. He-Laplace method was used to obtain the solution of the equations and expressions for the velocity field, temperature and concentration distribution were given for each case. Graphical results for various interesting parameters were analyzed and presented.Keywords: Plane Couette; Magnetohydrodynamic; Porous Medium; Chemical Reaction Paramete

ANALYSIS OF ENTROPY GENERATION DUE TO MAGNETOHYDRODYNAMIC COUPLE STRESS FLUID

We demonstrate the first reconfigurable photonic metamaterial controlled by electrical currents and magnetic fields, providing first practically useful solutions for sub-megahertz and high contrast modulation of metamaterial optical properties

Analysis of heat absorption viscoelastic exothermic chemical reactive fluid with temperature dependent viscosity under bimolecular kinetic

This study examines the boundary layer flow of variable viscosity, incompressible exothermic chemical reactive fluid with thermal radiation and asymmetric convective cooling under Bimolecular kinetic. The viscoelastic fluid flow along a vertical channel in the presence of a thermal buoyancy force and pressure gradient. Rosseland approximation is defined for the thick radiation heat flux in the energy equation with gray radiating liquid, non-scattering but with heat absorbing depending on wavelength. The convective heat exchange with the sorrounding temperature at the channel surface satisfied Newton’s law of cooling. The computational analysis of the dimensionless nonlinear governing equations is obtained using Weighted residual method (WRM). The solutions are employed to obtain the velocity field, energy profile, skin friction and Nusselt number of the flow. These are graphically presented and discussed to show the effect of some pertinent fluid parameters on the non-Newtonian liquid flow. It is observed that the heat source reaction terms need to be cautiously monitored and controlled to avoid reaction solution blow up

Transient Stage Comparison of Couette Flow under Step Shear Stress and Step Velocity Boundary Conditions

Couette flow has been widely used in many industrial and research processes, such as viscosity measurement. For the study on thixotropic viscosity, step-loading, which includes (1) step shear stress and (2) step velocity conditions, is widely used. Transient stages of Couette flow under both step wall shear stress and step wall velocity conditions were investigated. The relative coefficient of viscosity was proposed to reflect the transient process. Relative coefficients of viscosity, dimensionless velocities and dimensionless development times were derived and calculated numerically. This article quantifies the relative coefficients of viscosity as functions of dimensionless time and step ratios when the boundary is subjected to step changes. As expected, in the absence of step changes, the expressions reduce to being functions of dimensionless time. When step wall shear stresses are imposed, the relative coefficients of viscosity changes from the values of the step ratios to their steady-state value of 1. but With step-increasing wall velocities, the relative coefficients of viscosity decrease from positive infinity to 1. The relative coefficients of viscosity increase from negative infinity to 1 under the step-decreasing wall velocity condition. During the very initial stage, the relative coefficients of viscosity under step wall velocity conditions is further from 1 than the one under step wall shear stress conditions but the former reaches 1 faster. Dimensionless development times grow with the step ratio under the step-rising conditions and approaches the constant value of 1.785 under the step wall shear stress condition, and 0.537 under the step wall velocity condition respectively. The development times under the imposed step wall shear stress conditions are always larger than the same under the imposed step wall velocity conditions

The Twente turbulent Taylor-Couette (T3C) facility: Strongly turbulent (multiphase) flow between two independently rotating cylinders

A new turbulent Taylor-Couette system consisting of two independently rotating cylinders has been constructed. The gap between the cylinders has a height of 0.927 m, an inner radius of 0.200 m, and a variable outer radius (from 0.279 to 0.220 m). The maximum angular rotation rates of the inner and outer cylinder are 20 and 10 Hz, respectively, resulting in Reynolds numbers up to 3.4 x 10^6 with water as working fluid. With this Taylor-Couette system, the parameter space (Re_i, Re_o, {\eta}) extends to (2.0 x 10^6, {\pm}1.4 x 10^6, 0.716-0.909). The system is equipped with bubble injectors, temperature control, skin-friction drag sensors, and several local sensors for studying turbulent single-phase and two-phase flows. Inner cylinder load cells detect skin-friction drag via torque measurements. The clear acrylic outer cylinder allows the dynamics of the liquid flow and the dispersed phase (bubbles, particles, fibers, etc.) inside the gap to be investigated with specialized local sensors and nonintrusive optical imaging techniques. The system allows study of both Taylor-Couette flow in a high-Reynolds-number regime, and the mechanisms behind skin-friction drag alterations due to bubble injection, polymer injection, and surface hydrophobicity and roughness.Comment: 13 pages, 14 figure

Hall current and suction/injection effects on the entropy generation of third grade fluid

In this work, effects of Hall current and suction/injection on a steady, viscous, incompressible and electrically conducting third grade fluid past a semi-infinite plate with entropy generation is investigated. It is assumed that the fluid motion is induced by applied pressure gradient. Hot fluid is injected with a constant velocity at the injection wall while it is sucked off at the upper wall with the same velocity. The governing equations of Navier-Stoke, energy and entropy generation obtained are non-dimensionalised, the resulting dimensionless velocity and temperature profiles are solved by Adomian decomposition technique due to the nonlinearity of the coupled system of equations. The obtained solution for the velocity profile is validated by the exact solution and the existing one in literature at M = 0 and the analytical expressions for fluid velocity and temperature are utilized to calculate the entropy generation and irreversibility ratio. Various plots are presented and discussed. It is found that increasing Hall current parameter increases primary velocity, temperature, entropy generation and Bejan number while the reverse trend is observed when both suction/injection and magnetic field parameters are increased. It is also noticed that entropy production at the upper wall is due to heat transfer

Numerical Investigation of Entropy Generation in Unsteady MHD Generalized Couette Flow with Variable Electrical Conductivity

The thermodynamic second law analysis is utilized to investigate the inherent irreversibility in an unsteady hydromagnetic generalized Couette flow with variable electrical conductivity in the presence of induced electric field. Based on some simplified assumption, the model nonlinear governing equations are obtained and solved numerically using semidiscretization finite difference techniques. Effects of various thermophysical parameters on the fluid velocity, temperature, current density, skin friction, the Nusselt number, entropy generation number, and the Bejan number are presented graphically and discussed quantitatively