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3 International Journal of Applied Mechanics and Engineering

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Role of suction/injection on electromagnetohydrodynamics natural convection flow in a porous microchannel with electroosmotic effect

100%

Oni M. O. , Rilwan U.

International Journal of Applied Mechanics and Engineering

2023

tom Vol. 28, no. 4

94--113

This paper examined the role of suction/injection on time-dependent electromagnetohydrodynamics (EMHD) natural (free) convection flow in a vertical microchannel with electroosmotic effect. With the aid of Laplace transformation method, the governing energy and momentum equations are converted from partial differential equation (PDE) into ordinary differential equation (ODE) to obtain fluid temperature and velocity in Laplace domain. The semi-analytical solutions of the velocity profile and temperature distribution have been derived using the Riemann sum approximation. After which a MATLAB program was written to study the effects of Prandlt number Pr, Hartmann number Ha, electric field strength on x and z directions (Ex and Sz) and Grashof number Gr in fluid velocity, temperature, skin-friction and mass flow rate in terms of line graphs. Result shows the role of suction/injection parameter alters the temperature distribution and velocity profile, so also how effective the governing parameters contribute to the flow formation.

Analysis of transient natural convective flow of a nanofluid in a vertical tube

80%

Jha B. K. , Chitumu A. J. , Oni M. O.

International Journal of Applied Mechanics and Engineering

2021

tom Vol. 26, no. 2

31--46

An analysis into the transient natural convective flow of a nanofluid in a vertical tube is made. The governing equations of momentum, heat transfer and nanoparticle volume fraction are deduced, and the influence of the thermophoresis parameter and Brownian motion is incorporated. By direct integration and variation of the parameter, analytical solutions are obtained for flow formation and heat/mass transfer at steady-state. On the other hand, due to the complexity of same problem at transient state, a numerical solution is used to solve the discretized equations of motion using the implicit finite difference technique. The influence of the thermophoresis parameter and Brownian motion is noted and well discussed. For accuracy check, a numerical comparison is made between the steady state and transient state solution at large time; this comparison gives an excellent agreement. The role of various principal parameters on velocity profile, temperature, concentration of nanoparticles, Sherwood and Nusselt numbers are presented graphically and well discussed. It is noted that the buoyancy ratio decreases the fluid velocity significantly.

Start-off MHD electrokinetic Couette flow in an annulus: A Riemann-sum approximation approach

70%

Oni M. O. , Jha B. K. , Abba J. M. , Mundi B. I. , Adebayo O. H.

tom Vol. 29, no. 3

82--100

The time dependent Couette flow of an electrically conducting fluid in a horizontal annulus in the presence of electric potential and accelerated motion of the outer cylinder is investigated. The governing electric field potential as well as the momentum equations are obtained from Poisson–Boltzmann and Navier-Stokes equations respectively. As a promising tool for solving time-dependent problems, the Laplace transform technique is used to obtain analytical solution for electric field and velocity profile in Laplace domain. Using the Riemann-sum approximation simulation, the results are obtained numerically in time-domain. In the course of numerical and graphical representations of results, it is found that the magnitude of electrokinetic effect as well as Debye-Hückel parameter play important role in flow formation and mass flow rate in the horizontal annulus. Further, velocity, skin-friction and mass flow-rate decrease with increase in Debye-Hückel parameter at all-time regardless of the mode of application of magnetic field. In addition, mass flow-rate can be enhanced with increasing Hartmann number when the magnetic field fixed relative to the moving cylinder.