Abuzar Abid Siddiqui

Bio: Abuzar Abid Siddiqui is an academic researcher from Bahauddin Zakariya University. The author has contributed to research in topics: Newtonian fluid & Boundary value problem. The author has an hindex of 6, co-authored 16 publications receiving 104 citations. Previous affiliations of Abuzar Abid Siddiqui include Pennsylvania State University.

Natural convection in the ferrofluid enclosed in a porous and permeable cavity

Abstract: The thermal transfer in the water-based ferrofluid enclosed porous cavity attached with a novel permeable (suction/injection) chamber is investigated within this research. The mathematical analysis of the problem is fulfilled with the modified Rosensweig-model (mRm) accounting for the Darcy porous medium in cooperation with the energy equation. The relevant governing equations are numerically treated via the successive-over-relaxation method (SOR) based on a special finite difference scheme. The pertinent effects of physical parameters on the convection and heat transfer of the ferrofluid inside the cavity are examined in detail. It is determined that the Nusselt number enhances at the left wall but it is reduced at the right wall if one increases either (i) the concentration of the ferroparticles or (ii) the Lorentz force. But the effect of Kelvin force is different from the effect of the Lorentz force on the Nusselt number in the sense that; the Nusselt number decays at the left wall but it intensifies at the right wall if we increase the Lorentz force or its representative the Hartmann number. In addition, the Nusselt number at the left wall of the cavity rises about 1.4 times if the Hartmann number increases from 0 to 50. The problem setup in the current work may be useful in the applications regarding bio-medical, pharmaceutical and engineering industries. The generated results from the present work quantitatively as well as qualitatively match with the existing literature.

A New Theoretical Approach of Wall Transpiration in the Cavity Flow of the Ferrofluids

Abstract: An idea of permeable (suction/injection) chamber is proposed in the current work to control the secondary vortices appearing in the well-known lid-driven cavity flow by means of the water based ferrofluids. The Rosensweig model is conveniently adopted for the mathematical analysis of the physical problem. The governing equation of model is first transformed into the vorticity transport equation. A special finite difference method in association with the successive over-relaxation method (SOR) is then employed to numerically simulate the flow behavior. The effects of intensity of magnetic source (controlled by the Stuart number), aspect ratio of the cavity, rate of permeability (i.e., α p = V 0 U ), ratio of speed of suction/injection V 0 to the sliding-speed U of the upper wall of a cavity, and Reynolds number on the ferrofluid in the cavity are fully examined. It is found that the secondary vortices residing on the lower wall of the cavity are dissolved by the implementation of the suction/injection chamber. Their character is dependent on the rate of permeability. The intensity of magnetic source affects the system in such a way to alter the flow and to transport the fluid away from the magnetic source location. It also reduces the loading effects on the walls of the cavity. If the depth of cavity (or the aspect ratio) is increased, the secondary vortices join together to form a single secondary vortex. The number of secondary vortices is shown to increase if the Reynolds number is increased for both the clear fluid as well as the ferrofluids. The suction and injection create resistance in settlement of solid ferroparticles on the bottom. The results obtained are validated with the existing data in the literature and satisfactory agreement is observed. The presented problem may find applications in biomedical, pharmaceutical, and engineering industries.

Steady electro-osmotic flow of a micropolar fluid in a microchannel

Abstract: We have formulated and solved the boundary-value problem of steady, symmetric and one-dimensional electro-osmotic flow of a micropolar fluid in a uniform rectangular microchannel, under the action of a uniform applied electric field. The Helmholtz–Smoluchowski equation and velocity for micropolar fluids have also been formulated. Numerical solutions turn out to be virtually identical to the analytic solutions obtained after using the Debye–Huckel approximation, when the microchannel height exceeds the Debye length, provided that the zeta potential is sufficiently small in magnitude. For a fixed Debye length, the mid-channel fluid speed is linearly proportional to the microchannel height when the fluid is micropolar, but not when the fluid is simple Newtonian. The stress and the microrotation are dominant at and in the vicinity of the microchannel walls, regardless of the microchannel height. The mid-channel couple stress decreases, but the couple stress at the walls intensifies, as the microchannel height increases and the flow tends towards turbulence.

Non-steady electro-osmotic flow of a micropolar fluid in a microchannel

Abstract: We formulated the initial-boundary-value problem of non-steady electro-osmotic flow of a micropolar fluid in a rectangular microchannel of height much larger than the Debye length and length much larger the height. Solving the governing differential equations numerically when a spatially uniform electric field is applied as an impulse of finite magnitude, we found that the effect is instantaneous on the flow, just as for simple Newtonian fluids. The decay times of the fluid velocity and the microrotation, however, are smaller in micropolar fluids than in simple Newtonian fluids. The maximum magnitude of microrotation decreases as the micropolarity increases. The effect of microrotation on the stress tensor is more dominant than that of the fluid speed, and a threshold effect with respect to the magnitude of the zeta potential is evident in the spatial profile of the couple stress tensor. We expect similar trends even when the applied electric field varies over some finite interval of time.

Numerical Simulation of Asymmetric Merging Flow in a Rectangular Channel

Abstract: The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of the splitter plate was taken as a centreline of channel but here it is considered its different positions which cause the asymmetric behaviour of the flow field. The geometric parameter that controls the position of splitter is defined as splitter position parameter a. The plane Poiseuille flow is considered far from upstream and downstream of the splitter. This flow-problem is solved numerically by a numerical scheme comprising a fourth order method, followed by a special finite-method. This numerical scheme transforms the governing equations to system of finite-difference equations, which are solved by point S.O.R. iterative method. In addition, the results obtained are further refined and upgraded by Richardson Extrapolation method. The calculations are carried out for the ranges -1 α R 5. The results are compared with existing literature regarding the symmetric case (when a = 0) for velocity, vorticity and skin friction distributions. The comparison is very favourable. Moreover, the notable thing is that the decay of vorticity to its downstream value takes place over an increasingly longer scale of x as R increases for symmetric case but it is not so for asymmetric one.

Investigation on TiO2–Cu/H2O hybrid nanofluid with slip conditions in MHD peristaltic flow of Jeffrey material

Abstract: Slippage impacton peristaltic transport of MHD hybrid nanofluids (TiO2–Cu/H2O) in an asymmetric channel is addressed. Impact of viscous dissipation and Hall current are analyzed in the modeling as well. Constitutive expressions for viscoelastic Jeffery fluid are employed. The mathematical expressions of the problem are transformed into a set of ordinary differential equations by employing appropriate quantities. Well-known long wavelength assumption is invoked. The obtained dimensionless model is then numerically solved with the help of Adams–Bashforth method. The effects of sundry parameters on flow distributions are demonstrated via plots.

Thermal, microrotation, electromagnetic field and nanoparticle shape effects on Cu-CuO/blood flow in microvascular vessels.

Abstract: A thermal analysis of Cu-CuO/ blood nanofluids flow in asymmetric microchannel propagating with wave velocity is presented in this study. For the blood, a micropolar fluid model is considered to investigate the microrotation effects of blood flow. Thermal radiation effects and the influence of nanoparticle shape, electric double layer thickness, and electromagnetic fields on the flow are studied. Three types of nanoparticles shapes namely cylinder, bricks and platelets are taken into account. Governing equations are solved under the approximations of long wavelength, low Reynolds number, and Debye-Huckel linearization. Numerical computations are performed for the axial pressure gradient, axial velocity, spin velocity and temperature distribution. The effects of various physical parameters on flow and thermal characteristics are computed and their physical interpretation is also discussed. The outcomes indicate that the axial velocity of Cu-CuO/blood nanoparticles strongly depends on applied electromagnetic field and microrotation. The model's finding will be applicable in designing the smart electromagnetic micro pumps for the hemodialysis and lungs-on-chip devices for the pumping of the blood.

Electro-osmotic flow of couple stress fluids in a micro-channel propagated by peristalsis

Abstract: A mathematical model is developed for electro-osmotic peristaltic pumping of a non-Newtonian liquid in a deformable micro-channel. Stokes' couple stress fluid model is employed to represent realistic working liquids. The Poisson-Boltzmann equation for electric potential distribution is implemented owing to the presence of an electrical double layer (EDL) in the micro-channel. Using long wavelength, lubrication theory and Debye-Huckel approximations, the linearized transformed dimensionless boundary value problem is solved analytically. The influence of electro-osmotic parameter (inversely proportional to Debye length), maximum electro-osmotic velocity (a function of external applied electrical field) and couple stress parameter on axial velocity, volumetric flow rate, pressure gradient, local wall shear stress and stream function distributions is evaluated in detail with the aid of graphs. The Newtonian fluid case is retrieved as a special case with vanishing couple stress effects. With increasing the couple stress parameter there is a significant increase in the axial pressure gradient whereas the core axial velocity is reduced. An increase in the electro-osmotic parameter both induces flow acceleration in the core region (around the channel centreline) and it also enhances the axial pressure gradient substantially. The study is relevant in the simulation of novel smart bio-inspired space pumps, chromatography and medical micro-scale devices.