Unsteady free convection flow past a periodically accelerated vertical plate with Newtonian heating

2016 ◽  
Vol 26 (7) ◽  
pp. 2119-2138 ◽  
Author(s):  
M.C. Raju ◽  
S.V.K. Varma ◽  
A.J. Chamkha
Keyword(s):  
Mass Transfer ◽  
Free Convection ◽  
Skin Friction ◽  
Heat And Mass Transfer ◽  
Convection Flow ◽  
Convection Boundary Layer ◽  
Physical Parameters ◽  
Content Type ◽  
Flow Past ◽  
Laplace Transform Technique

Purpose The purpose of this paper is to present an analytical study for a problem of unsteady free convection boundary layer flow past a periodically accelerated vertical plate with Newtonian heating (NH). Design/methodology/approach The equations governing the flow are studied in the closed form by using the Laplace transform technique. The effects of various physical parameters are studied through graphs and the expressions for skin friction, Nusselt number and Sherwood number are also derived and discussed numerically. Findings It is observed that velocity, concentration and skin friction decrease with the increasing values of Sc whereas temperature distribution decreases in the increase in Pr in the presence of NH. Research limitations/implications This study is limited to a Newtonian fluid. This can be extended for non-Newtonian fluids. Practical implications Heat and mass transfer frequently occurs in chemically processed industries, distribution of temperature and moisture over agricultural fields, dispersion of fog and environment pollution and polymer production. Social implications Free convection flow of coupled heat and mass transfer occurs due to the temperature and concentration differences in the fluid as a result of driving forces. For example, in atmospheric flows, thermal convection resulting from heating of the earth by sunlight is affected differences in water vapor concentration. Originality/value The authors have studied heat and mass transfer effects on unsteady free convection boundary layer flow past a periodically accelerated vertical surface with NH, where the heat transfer rate from the bounding surface with a finite heat capacity is proportional to the local surface temperature, and which is usually termed as conjugate convective flow. The equations governing the flow are studied in the closed form by using the Laplace transform technique. The effects of various physical parameters are studied through graphs and the expression for skin friction also derived and discussed.

scholarly journals Heat and Mass Transfer of Unsteady Hydromagnetic Free Convection Flow Through Porous Medium Past a Vertical Plate with Uniform Surface Heat Flux

2017 ◽  
Vol 47 (3) ◽  
pp. 25-58 ◽  
Author(s):  
Mohamed Abd El-Aziz ◽  
Aishah S. Yahya
Keyword(s):  
Mass Transfer ◽  
Heat Flux ◽  
Porous Medium ◽  
Free Convection ◽  
Heat And Mass Transfer ◽  
Transport Model ◽  
Convection Flow ◽  
Physical Parameters ◽  
Free Convection Flow ◽  
Laplace Transform Technique

AbstractSimultaneous effects of thermal and concentration diffusions in unsteady magnetohydrodynamic free convection flow past a moving plate maintained at constant heat flux and embedded in a viscous fluid saturated porous medium is presented. The transport model employed includes the effects of thermal radiation, heat sink, Soret and chemical reaction. The fluid is considered as a gray absorbing-emitting but non-scattering medium and the Rosseland approximation in the energy equations is used to describe the radiative heat flux for optically thick fluid. The dimensionless coupled linear partial differential equations are solved by using Laplace transform technique. Numerical results for the velocity, temperature, concentration as well as the skin friction coefficient and the rates of heat and mass transfer are shown graphically for different values of physical parameters involved.

Transient Free Convection Flow Past an Infinite Moving Vertical Cylinder in a Stably Stratified Fluid

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
R. K. Deka ◽  
A. Paul
Keyword(s):  
Nusselt Number ◽  
Steady State ◽  
Skin Friction ◽  
Thermal Stratification ◽  
Fluid Velocity ◽  
Vertical Cylinder ◽  
Convection Flow ◽  
Physical Parameters ◽  
Flow Past ◽  
Laplace Transform Technique

This paper presents an analytical treatment for the unsteady one-dimensional natural convective flow past an infinite moving vertical cylinder in the presence of thermal stratification. Exact solutions of the dimensionless unsteady coupled linear governing equations are obtained, in terms of Bessel functions by the Laplace transform technique, for the tractable case of unit Prandtl number. Numerical computations for velocity, temperature, skin-friction, and Nusselt number are made for various set of physical parameters and presented in graphs. Due to the presence of thermal stratification, the fluid velocity and temperature approach steady state, whereas the corresponding flow in an unstratified fluid does not. The steady state is attained at smaller times as the stratification increases. Furthermore, in the presence of stratification, the skin-friction and Nusselt number approaches fixed value as time progresses, while for unstratified fluid, there is a gradual decrease as time increases.

Effects of Mass Transfer and Free-Convection Currents on the Flow Near a Moving Vertical Plate With Ramped Wall Temperature

2009 ◽  
Author(s):  
M. Narahari ◽  
Binay K. Dutta
Keyword(s):  
Mass Transfer ◽  
Free Convection ◽  
Skin Friction ◽  
Heat And Mass Transfer ◽  
Buoyancy Force ◽  
Vertical Plate ◽  
Flow Temperature ◽  
Thermal Buoyancy ◽  
Laplace Transform Technique ◽  
Thermal Buoyancy Force

A theoretical analysis to the problem of free convection flow induced by an infinite moving vertical plate subject to a ramped surface temperature with simultaneous mass transfer to or from the surface is presented. The plate temperature increases linearly over a specified period of time until it reaches a constant value. Diffusional mass transfer occurs at the surface contributing to the density gradient in the boundary layer. An exact analytical solution to the governing equations for flow, temperature and concentration with coupled boundary conditions in the dimensionless form have been developed using the Laplace transform technique. Heat and mass transfer at the plate are assumed to be purely diffusive in nature. The cases of impulsive start and uniformly accelerating start of the plate are considered and solutions for the flow, temperature and concentration fields are derived. The effects of different system parameters have been studied in terms of relevant dimensionless groups such as Grashof number (Gr), Prandtl number (Pr), Schmidt number (Sc), time (t) and the mass to thermal buoyancy ratio (N). The possible cases of the last parameter, namely N = 0 (the buoyancy force is due to thermal diffusion only), N > 0 (the mass buoyancy force acts in the same direction of thermal buoyancy force) and N < 0 (the mass buoyancy force acts in the opposite direction of thermal buoyancy force) are investigated and their effects on the velocity field and skin-friction are explicitly determined. The ramped temperature boundary condition predictably has an enhancing effect on the skin friction. The mass flux to the plate influences the velocity and hence the skin friction. A critical analysis of the coupled heat and mass transfer phenomena is provided. The free convection near a ramped temperature plate has also been compared with the flow near a plate with constant temperature as a limiting case.

scholarly journals Radiation and mass transfer effects on MHD free convection flow past a moving vertical cylinder in a porous medium

2011 ◽  
Vol 7 (1) ◽  
pp. 1-10 ◽  
Author(s):  
S. Suneetha ◽  
N. Bhaskar Reddy
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Free Convection ◽  
Vertical Cylinder ◽  
Mhd Flow ◽  
Convection Flow ◽  
Physical Parameters ◽  
Radiation Parameter ◽  
Grashof Number ◽  
Flow Past

The interaction of free convection with thermal radiation of a viscous incompressible unsteady MHD flow past a moving vertical cylinder with heat and mass transfer in a porous medium is analyzed. The fluid is a gray, absorbing-emitting but non-scattering medium and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing equations are solved by using an implicit finite-difference scheme of Crank-Nicolson type. The effects of various physical parameters such as thermal Grashof number, mass Grashof number, magnetic parameter, radiation parameter and Schmidt number on the velocity, temperature,  concentration,  local as well as average skin-friction, Nusselt number and Sherwood number for various parameters are computed and represented graphically. It is found that at small values of radiation parameter ,  the velocity and temperature of the fluid increases sharply near the cylinder as the time  increases. Also, an increase in the magnetic field leads to a decrease in the velocity and a rise in the temperature.As the permeability parameter increases,it is seen that the flow accelerates. This model finds applications in geophysics and engineering.DOI: 10.3329/jname.v7i1.2901

scholarly journals UNSTEADY MHD HEAT AND MASS TRANSFER FLOW OF A RADIATING FLUID PAST AN ACCELERATED INCLINED POROUS PLATE WITH HALL CURRENT

2017 ◽  
Vol 5 (7) ◽  
pp. 42-59
Author(s):  
G. Sivaiah ◽  
K. Jayarami Reddy
Keyword(s):  
Mass Transfer ◽  
Nusselt Number ◽  
Skin Friction ◽  
Heat And Mass Transfer ◽  
Sherwood Number ◽  
Hall Current ◽  
Porous Plate ◽  
Physical Parameters ◽  
Laplace Transform Technique ◽  
Transfer Flow

In this paper an analysis has been performed to study the effects of Hall current and radiation of MHD free convective heat and mass transfer flow of a radiating fluid past an accelerated inclined porous plate with hall current in presence of thermal diffusion and heat source. The solutions for velocity, temperature and concentration distributions are obtained by using Laplace transform technique. The expressions for skin friction, Nusselt number and Sherwood number are also derived. The variations in fluid velocity, temperature and species concentration are shown graphically, whereas numerical values of skin friction, Nusselt number and Sherwood number are presented in tabular form for various values of physical parameters.

Unsteady MHD Free Convective Heat and Mass Transfer Flow Past a Vertical Porous Plate in the Presence of Radiation and Chemical Reaction

2017 ◽  
Vol 6 (10) ◽  
pp. 116
Author(s):  
J. Buggaramulu ◽  
M. Venkatakrishna ◽  
Y. Harikrishna
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Chemical Reaction ◽  
Porous Plate ◽  
Physical Parameters ◽  
Governing Equations ◽  
Vertical Porous Plate ◽  
Flow Past ◽  
Transfer Flow

The objective of this paper is to analyze an unsteady MHD free convective heat and mass transfer boundary flow past a semi-infinite vertical porous plate immersed in a porous medium with radiation and chemical reaction. The governing equations of the flow field are solved numerical a two term perturbation method. The effects of the various parameters on the velocity, temperature and concentration profiles are presented graphically and values of skin-frication coefficient, Nusselt number and Sherwood number for various values of physical parameters are presented through tables.

Sign in / Sign up

Export Citation Format

Share Document