Resolving Local Reaction Environment toward an Optimized CO2-to-CO Conversion Performance

The local reaction environment, especially the electrode-electrolyte interface and the relevant hydrodynamic boundary layer in the vicinity of cathode, plays a vital role in defining the activity and selectivity of...

Numerical Analysis of Heat Transfer of Eyring Powell Fluid Using Double Stratification of Magneto-Hydrodynamic Boundary Layer Flow

Heat transfer fluids play a vital role in many engineering and industrial sectors such as power generation, chemical production, air-conditioning, transportation and microelectronics. Aim: To numerically investigate the effect of double stratification on magneto-hydrodynamic boundary layer flow and heat transfer of an Eyring-Powell fluid. Study Design: Eyring-Powell fluid is one of the non-Newtonian fluid that possess different characteristics thus different mathematical models have been formulated to describe such fluids by appropriate substitution into Navier-Stoke’s equations. The challenging complexity and the nature of the resultant equations are of great interest hence attract many investigations. Place and Duration of Study: Department of Mathematics and Actuarial Science, Kenyatta University, Nairobi, Kenya between December 2019 and October 2020. Methodology: The resultant nonlinear equations are transformed to linear differential equations by introducing appropriate similarity transformations. The resulting equations are solved numerically by simulating the predictor-corrector (P-C) method in matlab ode113. The results are graphically depicted and analysed to illustrate the effects of magnetic field, thermophoresis, thermal stratification, solutal stratification, material fluid parameters and Grashoff number on the fluid velocity, temperature, concentration, local Sherwood number and local Nusselt number. Results: The results show that increasing the magnetic field strength, thermophoresis, thermal stratification and solutal stratification lead to a decrease in the fluid velocity, temperature, Sherwood number, Nusselt number and skin friction while an increase in the magnetic field strength, thermal stratification, solutal stratification, and thermophoresis increases the fluid concentration. Conclusion: The parameters in this study can be varied to enhance heat ejection of Eyring-Powell fluid and applied in industries as a coolant or heat transfer fluid.

Flow Visualization of Footballs to Analyze the Factors Affecting their Aerodynamic Performance Using CFD

The motion of a football in air is influenced by the combination of various aerodynamic effects caused by the parameters such as velocity, surface roughness, panel orientation and shape. This paper analyzes the individual and combined effects of these parameters on the flight characteristics of various footballs using CFD Analysis. Four balls, a smooth sphere, a 32-panel conventional football, 14-panel Teamgeist and 6-panel Brazuca ball are subjected to different velocities of air flow over them, both in the laminar and turbulent regime, different surface roughness values and the influence of these parameters on the aerodynamics of the balls is evaluated by the drag force, drag coefficient and hydrodynamic boundary layer separation angle. The effect of the seam length, number of panels and panel orientation are also compared. The results of these effects are discussed later in the paper and are used to explain the knuckling effects and unpredictable trajectory of the Jabulani ball.

Unsteady MHD Free Convection by Passing Cobalt Nanoparticles Past an Accelerated Vertical Plate Through Porous Medium of Ethylene Glycol

This article studies , the effects of unsteady magneto-hydrodynamic boundary layer when cobalt nanoparticles where passed onto a vertical plate which is given an impulse by exponential acceleration through porous medium of ethylene glycol when thermal radiation is present ,parameters of absorption of heat and radiation, chemical reaction parameter, magnetic field in transverse direction are theoretically studied. We consider cobalt nanoparticles resembles to spherical structure and range of volume of nanoparticle concentration is basically less than or equal to 4%. Considering the boundary conditions we have formulated a governing equations of nanoparticles which is in the form of partial differential equations. The precise solutions for velocity, concentration and temperature profiles are obtained by plotting the graphs of the equations formed using Laplace Method using MATLAB software. This study of heat transfer in nanoparticles finds application in tribological aspect, biological fields dealing with molecular level cell interactions, improving thermal conductivity and commercial cooling applications. The most significant outcome of this study is found in the concentration profile where time is varied. We see that there is 68% decrease in concentration when the time interval chosen is 0.2, whereas the decrease is found to 55% when the interval is increased to 0.4 keeping the distance from vertical plate constant.