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Goālpāra, India

Ahmed S.,Fluid Mechanics Research | Kalita D.,Mangaldoi College
International Journal of Applied Engineering Research | Year: 2012

Unsteady MHD heat transfer by mixed convection flow of a viscous, incompressible, electrically-conducting, Newtonian and radiating fluid which is an optically thin gray gas over a vertical permeable plate taking into account the induced magnetic field has been investigated. The similarity solutions of the transformed dimensionless governing equations are obtained by series solution. It is found that, velocity is reduced considerably with a rise in conduction-radiation parameter (R a) or Hartmann number (M) whereas the skin friction is found to be markedly boosted with an increase in Magnetic Prandtl number (Pr m). An increase in magnetic body parameter (M) or Magnetic Prandtl number (Pr m) is found to escalate induced magnetic field whereas an increase in R a is shown to exert the opposite effect. The acquired knowledge in our study can be used by designers to control Magnetohydrodynamic (MHD) flow as suitable for a certain application. Applications of the study include laminar magneto-aerodynamics, materials processing and MHD propulsion thermo-fluid dynamics. © Research India Publications. Source


Ahmed S.,Fluid Mechanics Research | Zueco J.,Technical University of Cartagena
Chemical Engineering Communications | Year: 2011

In this study we have obtained an exact solution to the problem of heat and mass transfer in a rotating vertical porous channel taking into account the effects of Hall current. A strong magnetic field of uniform strength is applied along the axis of rotation. The entire system rotates about the axis normal to the plates with a uniform angular velocity. The porous channel is subjected to a constant suction=injection velocity as well as uniform free stream velocity. The nonlinear and coupled governing equations are solved by perturbation technique. The analytical expressions for primary and secondary velocity components, temperature and concentration fields, and shear stresses are obtained. The effects of the magnetic field, rotation of the channel, buoyancy force, Hall current, injection-suction parameter, and the temperature oscillation frequency are described during the course of discussion. The results are presented graphically and discussed. © Taylor & Francis Group, LLC. Source


Ahmed S.,Fluid Mechanics Research | Zueco J.,Technical University of Cartagena | Lopez-Ochoa L.M.,University of La Rioja
Chemical Engineering Communications | Year: 2014

An analysis was carried out numerically to study unsteady heat and mass transfer by free convection flow of a viscous, incompressible, electrically conducting Newtonian fluid along a vertical permeable plate under the action of transverse magnetic field taking into account thermal radiation as well as homogeneous chemical reaction of first order. The fluid considered here is an optically thin gray gas, absorbing-emitting radiation, but a non-scattering medium. The porous plate was subjected to a constant suction velocity with variable surface temperature and concentration. The dimensionless governing coupled, nonlinear boundary layer partial differential equations were solved by an efficient, accurate, extensively validated, and unconditionally stable finite difference scheme of the Crank-Nicolson type. The velocity, temperature, and concentration fields were studied for the effects of Hartmann number (M), radiation parameter (R), chemical reaction (K), and Schmidt number (Sc). The local skin friction, Nusselt number, and Sherwood number are also presented and analyzed graphically. It is found that velocity is reduced considerably with a rise in the magnetic body parameter (M), whereas the temperature and concentration are found to be markedly boosted with an increase in the magnetic body parameter (M). An increase in the conduction-radiation parameter (R) is found to escalate the local skin friction (τ), Nusselt number, and concentration, whereas an increase in the conduction-radiation parameter (R) is shown to exert the opposite effect on either velocity or temperature field. Similarly, the local skin friction and the Sherwood number are both considerably increased with an increase in the chemical reaction parameter. Possible applications of the present study include laminar magneto-aerodynamics, materials processing, and MHD propulsion thermo-fluid dynamics. © 2014 Copyright Taylor and Francis Group, LLC. Source


Ahmed S.,Fluid Mechanics Research
Journal of Engineering Physics and Thermophysics | Year: 2011

The influence of thermal radiation and chemical reaction on the steady MHD heat and mass transfer by a mixed convective flow of a viscous, incompressible, electrically conducting Newtonian fluid (an optically thin gray gas) past a vertical permeable plate was investigated with account for the induced magnetic field. The similarity solutions of the transformed nondimensional governing equations are obtained by the series solution technique. The influence of numerous parameters on the process characteristics is studied. ©2011 Springer Science+Business Media, Inc. Source


Ting F.,South Dakota State University | Lai W.T.,Fluid Mechanics Research | Khoo M.Y.C.,Fluid Mechanics Research
Proceedings of the 18th Australasian Fluid Mechanics Conference, AFMC 2012 | Year: 2012

The present effort utilized the volumetric three-component velocimetry (V3V) technique to capture instantaneous velocity volumes in wave generation water flume tunnel. The measurements were taken for the volume from the bottom of the flume to the water surface. In this case structures of the vortices generated by the Spilling wave and the Plunging wave could be measured. The goal of these measurements was to understand the mechanism of such vortex generation. Since air was entrained by the wave, a large amount of bubbles existed in the liquid. This posed a challenge for the measurements. One solution to remove the bubble image for the velocity measurements was to use fluorescent seed particles to allow only the seed particles to be seen. The water flow was seeded with fluorescent seed particles of 107μm. The volume of 140 mm by 140 mm by 80 mm was illuminated with a 200 mJ/pulse, dual-cavity Nd:YAG laser. Particle images were captured by the volumetric 3-component velocimetry (V3V) camera system. Three high pass filters of 560 nm were used for the camera to allow the fluorescent signal generated by the particles to be captured. Velocity fields of the waves with more than 100,000 vectors were generated to give the 3D3C information. Source

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