Vol 1, No 1

Table of Contents


Inclined Magneticfield and Chemical Reaction Effects on Flow over a Semi Infinite Vertical Porous Plate through Porous Medium PDF
V. Sugunamma, N. Sandeep, P.Mohan Krishna, Ramana Bahunadam

We analyse the MHD, Radiation and chemical reaction effects on unsteady flow, heat and mass transfer characteristics in a viscous, incompressible and electrically conducting fluid over a semi infinite vertical porous plate through porous media in presence of inclined magnetic field. The porous plate is subjected to a transverse variable suction velocity. The transient, non-linear and coupled governing equations have been solved adopting a perturbative series expansion about a small parameter, ε. The effects of governing parameters on the flow variables are discussed graphically.

Estimation of Global Solar Radiation in Onitsha and Calabar Using Empirical Models PDF
M. N. Nnabuchi, J. E. Ekpe, G. F Ibeh

Understanding solar radiation data is essential for modelling solar energy systems. The purpose of the present study was to estimate global solar radiation on horizontal surface using meteorological parameters for a period of eleven years (1996 – 2006). Monthly average global solar radiation, H has been estimated for Onitsha and Calabar, Nigeria using predicting models generated by simple linear and multiple regression analyses. The models included a one variable model with relative humidity as the independent variable and two three-variable models correlating H with relative humidity and each of average temperature, cloudiness index and number of sunshine hours. The values of the global solar radiation estimated by the models and the measured solar radiation were tested using the mean bias error (MBE), root mean square error (RMSE) and mean percentage error (MPE) statiscal techniques. The values of the correlation coefficient (CC) were also determined for each model. The model that indicate a good agreement between the measured and estimated values for Onitsha and Calabar are  and  respectively. The developed models can be used for estimating global solar radiation in Onitsha and Calabar and other locations with similar climatic factors.

Chemically Deposited Cuprous Oxide Thin Film on Titanium Oxide for Solar Applications PDF
P.E Agbo, G. F Ibeh, S. O. Okeke, J. E Epke

Semiconducting cuprous oxide film (shell) was prepared by chemical bath method onto chemically bath deposited Titanium oxide thin film (core). The deposited films were treated under various annealing temperature up to 673K in order to determine the effects of thermal annealing on the structural and optical properties of the film. Our results showed that there is more crystallization and more orientation of the crystal growth with increase in temperature. TiO2/Cu2O core/shell thin film has a in the range of 0.8 – 3.5 m-1. The optical band gap lies between 2.99eV- 4.00eV. The properties indicates that the thin film can be used as coatings for suppression of UV radiations, in thermal control and solar control coating, electrical isolation and so on.

Acoustic Wave Propagation in Hexagonal MgTe, ZnTe and CdTe Compounds PDF
Pramod Kumar Yadawa

The acoustic wave propagation in the hexagonal structured materials MgTe, ZnTe and CdTe have been studied at room temperature. In this paper, the orientation dependence of three types of acoustic wave velocity and Debye average velocity have been calculated using second order elastic constants. The six second order elastic constants are calculated for theses materials at 300 K using Lenard-Jones Potential. An anomalous behaviour in orientation dependent acoustic wave velocity is obtained which is due to the combined effect of elastic constants and density. These velocity data are important for their structural information and to differentiate them from third group nitrides and laves-phase compounds. Obtained results, together with other well known physical properties, may expand future prospects for the applications and study of these materials.

Effects of radiation and viscous dissipation on unsteady free convective flow past a moving vertical porous plate embedded in a porous medium PDF
Sanatan Das, Mrinal Jana, Rabindra Nath Jana
Effects of radiation on unsteady free convection flow of a viscousincompressible fluid past a moving vertical plate embedded in aporous medium on taking  viscous dissipation into account havebeen studied. The governing partial differential equations havebeen solved numerically by applying a Crank - Nicolson's type ofimplicit finite difference method with a tri-diagonal matrixmanipulation and an iterative procedure. The variations of thefluid velocity and temperature are presented graphically. It isfound that the radiation decelerates the fluid velocity. The fluidvelocity increases with an increase in Darcy number. An increasein Eckert number leads to rise in fluid velocity and temperature.Further, it is found that the magnitude of the shear stress at theplate increases with an increase in either radiation parameter orPrandtl number. The rate of heat transfer at the plate increaseswith an increase in radiation parameter. This model findsapplications in geophysics, astrophysics and also in the design ofhigh temperature industrial processing systems.

Aligned Magnetic Field and Chemical Reaction Effects on Flow past a Vertical Oscillating Plate through Porous Medium PDF
N. Sandeep, V. Sugunamma

Present paper deals with the first order chemical reaction effects on unsteady free convective flow of a viscous incompressible flow past an infinite isothermal vertical oscillating plate with mass transfer in the presence of aligned magnetic field and heat generation /absorption. Exact solution for the dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity, temperature and concentration are studied for different parameters.

Volumetric and Thermodynamic Parameters of Ɩ-Leucine in Ethanol+ Water Mixtures at Different Temperatures PDF
Arun B. Nikumbh, Ganesh K. Kulkarni

Densities and viscosities of L-leucine in aqueous solutions of ethanol (1 to 10 mass %) have been measured at 298.15, 303.15, 308.15, 310.15 and 313.15 K. These data have been used to calculate apparent molar volume,, limiting apparent molar volume,  and the slopes, Sv, transfer volumes, , Falkenhagen Coefficient, A and Jones – Dole coefficient, B. These parameters have been used to discuss the solute-solute and solute-solvent interactions in these systems.

Exploring Viable Methods of Evaluating and Computing Vehicular Drag and Rolling Friction Force Coefficients by Applying Principles of Geometric Similitude PDF
Sanwar A. Sunny
The current study focuses on simple methods of quantifying vehicular drag and rolling resistance coefficients. It highlights the relationship between the drag coefficients (CD) of two models of varying scales but sharing geometric and dynamic similitude and also describe a simple, small scale and low cost, yet comprehensive approach to quantifying the automotive coefficient of Rolling Resistance or Friction (Crr), also known as the Rolling Resistance Coefficient (or RRC). Applying principles of fluid mechanics, especially Bernoulli’s law and by scaling models using Reynold’s Number (Re) and the Buckingham Pi Theorem at varying velocities u0, drag forces, the drag forces FD were supplementedby conducting simple wind tunnel tests. Real drag analysis show a 10% deviation from the literature data, contributed to negligence of the governing flow equations of Navier Stokes, such as modeling principles relative to turbulence. Some computational flow modeling principles were briefly discussed. For rolling friction coefficient method, coast down and dynamic speed trap tests of scaled models were conducted under varying body weighted conditions to converge on the value, where a high speed camera monitored the motion of the vehicle. The experiment produced different equations of motion which were then solved analytically by numerical analysis techniques to compute the rolling friction coefficient. Initial guesses in the least square optimization iterations provided coefficient values where drag forces were normalized (Crr of 0.0116). Studies were compared with literature and direct scaling abilities were attributed for quantifying the normalized value.

Magnetic Field and Chemical Reaction Effects on Convective Flow of Dusty Viscous Fluid PDF
P. Mohan Krishna, V. Sugunamma, N. Sandeep

In this paper we analyses the laminar convective flow of a dusty viscous fluid of non conducting walls in the presence of transverse magnetic field with volume fraction and the first order chemical reaction is taken into consideration. An exact analytic solution is obtained for the temperature and concentration fields by using perturbative technique from these temperature and concentration fields, we obtain numerical solution for the velocity field  and we analyze the effects of velocity, temperature and concentration of the fluid at the various parameters as  t (time), M (Magnetic parameter), Pr(Prandtl number) ,Gr (Grashof number), K1(Chemical reaction parameter).From these we observed that increase in transverse  magnetic field causes the decrease of velocity of the fluid and fluid temperature decreases by increase in prandtl number and Concentration profile increases by increase in chemical reaction parameter.

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