Magnetohydrodynamic Peristaltic flow of a couple stress with heat and mass transfer of a Jeffery fluid in a tube through porous medium
The effects couple stress on the unsteady flow of a couple stress fluid an incompressible non-Newtonian (Jeffrey) fluid through porous medium have been discussed. The thermal diffusion thermo effect are taken to our consideration. Analytical expression for the axial velocity, stream function and axial pressure gradient are established. The flow is investigated in a wave frame of reference moving with the velocity of the wave. The non-linear partial differential equations which govern this problem are simplified by making the assumptions of long wave length approximation. The analytical formula of the velocity and temperature have been obtained in terms of Bessel function of first and second kinds. In addition, it has been illustrated graphically for significant various parameters such as, magnetic parameter, couple stress parameter, permeability parameter, and thermal parameters .
Couette flow of a third-grade fluid with variable magnetic field
This investigation deals with the analytic solution for the time-dependent flow of an incompressible third-grade fluid which is under the influence of a magnetic field of variable strength. The fluid is in an annular region between two coaxial cylinders. The motion is induced due to an inner cylinder with arbitrary velocity. Group theoretic methods are employed to analyse the nonlinear problem and a solution for the velocity field is obtained analytically.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.