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 .
Peristaltic pumping with long wavelengths at low Reynolds number
Pumping by means of an infinite train of peristaltic waves is investigated under conditions for which the relevant Reynolds number is small enough for inertial effects to be negligible and the wavelength to diameter ratio is large enough for the pressure to be considered uniform over the cross-section. Theoretical results are presented for both plane and axisymmetric geometries, and for amplitude ratios ranging from zero to full occlusion. For a given amplitude ratio, the theoretical pressure rise per wavelength decreases linearly with increasing time-mean flow. An experiment with a quasi-two-dimensional apparatus confirmed the theoretical values. Calculations of the detailed fluid motions reveal that under many conditions of operation the net time-mean flow is the algebraic difference between a forward time-mean flow in the core of the tube and a backward (‘reflux’) time-mean flow near the periphery. The percentage of reflux flow can be very high. This reflux phenomenon is probably of physiologic significance in the functioning of the ureter and the gastro-intestinal system. A second fluid-mechanical peculiarity with physiological implications is that of ‘trapping’: under certain conditions an internally circulating bolus of fluid, lying about the axis, is transported with the wave speed as though it were trapped by the wave.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.