Dufour and Soret Effects of a Transient Free Convective Flow with Radiative Heat Transfer Past a Flat Plate Moving Through a Binary Mixture.

An approximate numerical solution for the Dufour and Soret effects of a transient free convective flow with radiative heat transfer past a flat plate moving through a binary mixture for a Sisko fluid has been obtained by solving the governing equations using numerical technique. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow is influenced appreciably by the chemical reaction, heat source and suction or injection at the wall and also the influence of Dufour and Soret in Sisko fluid. A parametric study illustrating the influence of H and m on the skin friction, Nusselt number, and Sherwood number is conducted. The obtained results are presented graphically and in tabular form and physical aspects of the problem are discussed

Thermal explosion analysis of a strong exothermic chemical reaction with variable pre-exponential factor in a spherical vessel

This study is devoted to investigate the analysis of thermal explosion of a strong exothermic chemical reaction with variable pre-exponential factor in a spherical vessel. The steady state solutions for strong exothermic decomposition of a combustible material uniformly distributed in a heated spherical vessel under Bimolecular, Arrhenius and Sensitised reaction rates. Analytical solutions are constructed for the governing nonlinear boundary-value problem using perturbation technique together with a special type of Hermite-Padé approximants and important properties of the temperature field including bifurcations and thermal criticality are discussed

Sustaining governance: the case for leadership

This chapter has three core aims. First, to discuss the concepts of governance and leadership while drawing upon key literatures and qualitative data to make sense of the factors that can enable leadership to sustain governance systems. Second, the chapter explores the practice of leadership at the Greater London Authority (GLA) level in the United Kingdom (UK) in order to establish features synonymous with the practice of leadership. Third, the relations between governance and leadership are explored so as to better understand how the latter is employed in sustaining the governance process at the GLA level in the UK

Unsteady three-dimensional MHD flow and mass transfer in a porous space in the presence of thermal radiation

Unsteady three-dimensional MHD flow and mass transfer in a porous is presented here by taking into account of thermal radiation. The governing fundamental equations are first transformed into system of ordinary differential equations using self similar transformation and they are solved numerically by using the sixth-order Runge-Kutta-Fehlberg method with shooting technique for some values of the physical parameters embedded in the flow model. Important features of the flow and heat transfer characteristic for different values of thermal radiation, magnetic field and chemical reaction are analyzed and discussed. Numerical results for the velocities, temperature and concentration profiles for a prescribed magnetic field, thermal radiation and chemical reaction parameters as well as the development of the local skin-friction coefficient, local Nusselt number and Sherwood number are reported graphically for various parametric conditions to show interesting aspect of the numerical solution

Buoyancy Effects on Thermal Boundary Layer Over a Vertical Plate With a Convective Surface Boundary Condition

This study aims to analyze the effects of thermal buoyancy on the laminar boundary layer about a vertical plate in a uniform stream of fluid under a convective surface boundary condition. Using a similarity variable, the governing nonlinear partial differential equations have been transformed into a set of coupled nonlinear ordinary differential equations, which are solved numerically by applying shooting iteration technique together with fourth-order Runge–Kutta integration scheme. The variations in dimensionless surface temperature and fluid-solid interface characteristics for different values of Prandtl number (Pr), local Grashof number Grx, and local convective heat transfer parameter Bix are graphed and tabulated. A comparison with previously published results on special case of the problem shows excellent agreement

Effects of Soret, Dufour, chemical reaction, thermal radiation and volumentric heat generation/absorption on mixed convection stagnation point flow on an Iso-thermal vertical plate in porous media

A mathematical model is analyzed in order to study the effects of Soret, Dufour, chemical reaction, thermal radiation and volumentric heat generation/absorption on mixed convection stagnation point flow on an Iso-thermal vertical plate in a porous media. The governing partial differential equations are transformed into set of coupled ordinary differential equations, which are solved numerically using Runge-Kutta sixth order method along with shooting technique. The physical interpretation to this expression is assigned through graphs and tables for the wall shear stress , Nusselt number and Sherwood number . Results were compared with the existing literature and showed a perfect agreement. Similarly, results showed that the fields were influenced appreciably by the effects of the governing parameters: Soret number Sr, Dufour number Df, chemical reaction parameter γ, thermal radiation parameter Ra, order of reactions n, thermal Grashof number GT, solutal Grashof number GC, Prandtl number Pr, permeability parameter K, rate of heat generation/absorption parameter S, and magnetic field strength parameter M. It was evident that for some kind of mixtures such as the light and medium molecular weight, the Soret and Dufour’s effects should be considered as well

UNSTEADY MIXED CONVECTION WITH SORET AND DUFOUR EFFECTS PAST A POROUS PLATE MOVING THROUGH A BINARY MIXTURE OF CHEMICALLY REACTING FLUID

This study investigates the unsteady mixed convection flow past a vertical porous flat plate moving through a binary mixture in the presence of radiative heat transfer and nth-order Arrhenius type of irreversible chemical reaction by taking into account the diffusion-thermal (Dufour) and thermo-diffusion (Soret) effects. Assuming an optically thin radiating fluid and using a local similarity variable, the governing nonlinear partial differential equations have been transformed into a set of coupled nonlinear ordinary differential equations, which are solved numerically by applying shooting iteration technique together with fourth-order Runge-Kutta integration scheme. Graphical results for the dimensionless velocity, temperature, and concentration distributions are shown for various values of the thermophysical parameters controlling the flow regime. Finally, numerical values of physical quantities, such as the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are presented in tabular form

An Empirical Comparison of Multiple Imputation Methods for Categorical Data

Multiple imputation is a common approach for dealing with missing values in statistical databases. The imputer fills in missing values with draws from predictive models estimated from the observed data, resulting in multiple, completed versions of the database. Researchers have developed a variety of default routines to implement multiple imputation; however, there has been limited research comparing the performance of these methods, particularly for categorical data. We use simulation studies to compare repeated sampling properties of three default multiple imputation methods for categorical data, including chained equations using generalized linear models, chained equations using classification and regression trees, and a fully Bayesian joint distribution based on Dirichlet Process mixture models. We base the simulations on categorical data from the American Community Survey. In the circumstances of this study, the results suggest that default chained equations approaches based on generalized linear models are dominated by the default regression tree and Bayesian mixture model approaches. They also suggest competing advantages for the regression tree and Bayesian mixture model approaches, making both reasonable default engines for multiple imputation of categorical data. A supplementary material for this article is available online

Analysis of the Effect of Viscous Dissipation on the Temperature Profile of the Laminar Flow in a Channel Filled with Saturated Porous Media.

The effect of viscous dissipation on the temperature profile of the laminar flow in a channel filled with saturated porous media is analyzed. The source of inspiration of this work could be found in Makinde et al. [4]. In this new paper, we include the viscous dissipation term which has an effect on the temperature profile of the fluid flow in the channel. The Brinkman model was employed. Velocity and temperature profiles are obtained for large Brinkman number using Pascal programming language and Maple software packages. Generally our result shows that the fluid temperature decreases with a decrease in porous media permeability (s increases) as the Brinkman number Br, increases

Hydromagnetic mixed convection stagnation point flow with radiative heat and mass transfer past a vertical plate embedded in a porous medium

A study has been carried out to obtain the solutions for hydromagnetic mixed convection stagnation point flow with radiative heat and mass transfer past a vertical plate embedded in a porous medium. The governing two dimensional equations are transformed using a similarity transformation and then solved numerically by shooting method coupled with Runge-Kutta iteration technique. Comparison with previously published work is performed and full agreement is obtained. A parametric study illustrating the influence of the magnetic field parameter, thermal radiation parameter, thermal Grashof number, Grashof numbers, Prandtl number, Schmidt number, on the velocity, temperature, and concentration field as well as the local friction coefficient, the local Nusselt number and the Sherwood number is carried out. The results are illustrated graphically and in tabular form to depict special features of the solutions