3,060 research outputs found
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
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
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
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
Combined effects of internal heat generation and buoyancy force on boundary layer over a vertical plate with a convective surface boundary condition
This paper considers the effect of buoyancy force and internal heat generation on laminar
thermal boundary layer over a vertical plate with a convective surface boundary condition. We
assumed that left surface of the plate is in contact with a hot fluid while a stream of cold fluid flows
steadily over the right surface with a heat source that decays exponentially. Using a similarity variable,
the steady state governing non-linear partial differential equations have been transformed into a set of
coupled non-linear ordinary differential equations, which are solved numerically by applying shooting
iteration technique together with fourth order Runge-Kutta integration scheme. The effects of Prandtl
number, local Biot number, the internal heat generation parameter and the local Grashof number on
the velocity and temperature profiles are illustrated and interpreted in physical terms. A comparison
with previously published results on special case of the problem shows excellent agreemen
- …