Usha R

A qualitative study of the effect of Poiseuille flow on the peristaltic transport of a particle-fluid suspension has been investigated in a two-dimensional mathematical model of peristalsis for the case when the wall of the channel executes a sinusoidal motion of small amplitude. The method of Frobenius series solution has been used to obtain a series solution for arbitrary values of Reynolds number and Poiseuille flow parameter. It is observed that the mean reversal flow is strongly dependent on the Poiseuille flow. Also, the effect of interaction is that the point of flow reversal is shifted from the center of the channel towards the boundaries.

An analysis of a laminar squeeze flow of an incompressible Newtonian fluid between parallel plane annuli is presented. The local and convective inertia of the flow are considered in the investigation. The solution is obtained as a power series in a single nondimensional parameter (squeeze Reynolds number) S, for small values of S. Expressions for the pressure and load capacity are given and are compared with those based on the assumption of inertialess flow. As applications, the constant velocity squeezing state and the case when the walls perform reciprocating harmonic oscillations with finite amplitude are considered. The changes in load capacity with the changes in the parameters that govern the motion have been investigated. © 1998 by ASME.

The axisymmetric motion of a fluid caused by an unsteady stretching surface that has relevance in extrusion process and bioengineering has been investigated. It has been shown that if the unsteady stretching velocity is prescribed by rb/(1-αt), then the problem admits a similarity solution which gives much insight to the character of solutions. The asymptotic and numerical solutions are obtained and they could be used in the testing of computer codes or analytical models of more realistic engineering systems. The results are governed by a nondimensional unsteady parameter S and it has been observed that no similarity solutions exist for S > 4. © 1995 by ASME.

The squeeze flow of an electrically conducting fluid between two parallel disks with injection at the lower porous disk in the presence of a magnetic field applied perpendicular to the disk is investigated. Analytic solutions are obtained through the use of a regular perturbation scheme. The results show that the effect of injection is to increase the load carrying capacity in the hydromagnetic squeeze film and this increase is more than that observed without injection.

A particle-fluid suspension model is applied to the problem of pulsatile blood flow through a circular tube under the influence of body acceleration. With the help of finite Hankel and Laplace transforms, analytic expressions for axial velocity for both fluid and particle phase, fluid acceleration, wall shear stress and instantaneous flow rate have been obtained. It is observed that the solutions can be used for all feasible values of pulsatile and body acceleration Reynolds numbers Rp and Rb. Using physiological data, the following qualitative and quantitative results have been obtained. The amplitude Qb of instantaneous flow rate due to body acceleration decreases as the tube radius decreases. The effect of the volume fraction of particle C on Qb is to increase it with increase of C in arteriole and to decrease Qb as C increases in coronary and femoral arteries. The maximum of the axial velocity and fluid acceleration shifts from the axis of the tube to the vicinity of the tube wall as the tube diameter increases. The effect of C on the velocity and acceleration are nonuniform. The wall shear amplitude τb due to body acceleration increases as the tube diameter decreases from femoral to coronary and a further decrease in the tube diameter leads to a decrease in τb. The effects of C on τb are again nonuniform.

A viscous and electrically conducting fluid separates a rotating disk and a parallel non-rotating disk. A magnetic field of intensity B0 is applied perpendicular to the disks. As the two disks are squeezed closer together, increased viscous torque is transmitted to the rotating disk. The non-similar problem is solved using a perturbation in the small squeeze number. The effect of magnetic field on the braking action is discussed for the conditions of the top disk moving with constant velocity or constant force, while the bottom disk rotates with constant angular velocity.

An exact similarity solution has been obtained for the magnetohydrodynamic squeeze flow between two parallel disks with suction or injection at the porous disk. The disks, at time t*, are spaced a distance H(1 − α*)1/2 apart and a magnetic field proportional to B0(1 − αt*)−1/2 is applied perpendicular to the disks. Approximate analytic solutions are given and a numerical solution to the resulting nonlinear ordinary differential equation is obtained. The effects of magnetic forces on the velocity profiles and on the normal forces which the fluid exerts on the disks with suction or injection on the stationary porous disk are studied. It has been found that the effect of injection is to increase the load carrying capacity and it is the reverse in the case of suction. © 1997 ASME.

An analysis is presented for the laminar squeezing flow of an incompressible power-law fluid between parallel plane annuli using the modified lubrication theory and energy integral method. The local and the convective inertia of the flow are considered in the investigation. Analytical expressions for the load capacity of the squeeze film are obtained by both methods and are compared with those based on the assumption of inertialess flow. It is obsvered that the inertia correction for the load capacity is more significant for pseudo-plastic fluids, n < 1. For a Newtonian fluid, n = 1, expressions are obtained by using both methods and are compared with the a vailable results.

The present study extends the two-dimensional analysis of peristaltic transport of particle-fluid suspension by Srivastava and Srivastava to include an elastic or viscoelastic wall. This particulate suspension-solid interaction problem is investigated by considering equations of motion of the particle phase, fluid phase and the deformable boundaries. The wall characteristics appear in their equations of motion and they are solved to represent the boundary conditions of particulate suspension motion. It is observed that when the walls of the channel are elastic, pure peristalsis involves flow reversal only at the center of the channel. This position shifts drastically to the boundaries, if viscous damping forces are considered. The presence of the particles favours the reversal flow.