scholarly journals Thermo-diffusion effects on the magnetohydrodynamic natural convection flow of a chemically reactive Brinkman type nanofluid in a porous medium

2019 ◽  
Vol 51 (2) ◽  
pp. 168-179 ◽  
Author(s):  
G. S. Seth ◽  
R. Kumar ◽  
R. Tripathi
Keyword(s):  
Natural Convection ◽  
Skin Friction ◽  
Fluid Velocity ◽  
Surface Concentration ◽  
Convection Flow ◽  
Fluid Temperature ◽  
Species Concentration ◽  
Electrically Conducting ◽  
Laplace Transform Technique ◽  
Mass Transfers

An investigation on the unsteady MHD natural convection heat and mass transfer flow of an electrically conducting, viscous, incompressible, chemically reactive and heat-absorbing nanofluid of Brinkman type past an exponentially accelerated moving vertical plate with ramped wall temperature and ramped surface concentration is carried out. Governing equations are non-dimensionalized and Laplace Transform Technique is used to find the exact solutions for fluid velocity, fluid temperature and species concentration. The quantities of physical interest, i.e. skin friction, rates of heat and mass transfers at the plate are also calculated. Numerical results for the velocity, temperature and species concentration of the fluid are demonstrated with the help of graphs whereas those of skin friction, rate of heat and mass transfers at the plate are displayed in tables for various flow parameters.

scholarly journals Skin-friction for unsteady free convection MHD flow between two heated vertical parallel plates

2006 ◽  
Vol 33 (4) ◽  
pp. 259-280 ◽  
Author(s):  
Gopal Singha ◽  
P.N. Deka
Keyword(s):  
Free Convection ◽  
Skin Friction ◽  
Mhd Flow ◽  
Reynolds Numbers ◽  
Magnetic Reynolds Number ◽  
Convection Flow ◽  
Fluid Temperature ◽  
Parallel Plates ◽  
Electrically Conducting ◽  
Induced Field

Unsteady viscous incompressible free convection flow of an electrically conducting fluid between two heated vertical parallel plates is considered in the presence of a uniform magnetic field applied transversely to the flow. The induce field along the lines of motion varies transversely to the flow and the fluid temperature changing with time. An analytical solution for velocity, induced field and the temperature distributions are obtained for small and large magnetic Reynolds numbers. The skin-friction at the two plates is obtained. Velocity distribution, induced field and skin-friction are plotted against the distance from the plates. It has been observed that with the increase in Rm, the magnetic Reynolds number, at constant M, the Hartmann number, leads to an increase in the skin-friction gradually. But with the increase in M, at constant Rm, the skin-friction decreases.

scholarly journals Effect of Variable Viscosity on Natural Convection Flow Between Vertical Parallel Plates in the Presence of Heat Generation/Absorption

2019 ◽  
pp. 1-15
Author(s):  
Tada M. Kabir ◽  
Abiodun O. Ajibade
Keyword(s):  
Natural Convection ◽  
Skin Friction ◽  
Heat Generation ◽  
Variable Viscosity ◽  
Nonlinear Differential Equations ◽  
Convection Flow ◽  
Physical Parameters ◽  
Fluid Temperature ◽  
Parallel Plates ◽  
Natural Convection Flow

The present article was aimed at investigating the effects of variable viscosity on natural convection flow between vertical parallel plates in the presence of heat generation/absorption. The nonlinear differential equations governing the flow were solved using Homotopy perturbation method. The impacts of the several governing parameters on the velocity and temperature profiles are presented graphically and values of skin friction, rate of heat transfer, mass flux and mean temperature for various values of physical parameters are presented through tables. In the course of computation, it was revealed that viscosity  ontributes to decrease velocity and hence reduced resistance to flow. It was also discovered that as the heat generation increases, fluid temperature and velocity increase, while it decrease with the increase in heat absorption. Finally, it was concluded that the skin friction on both plates increase as viscosity increases.

MHD Double Diffusive Natural Convection Flow Over Exponentially Accelerated Inclined Plate

2016 ◽  
Vol 33 (01) ◽  
pp. 87-99 ◽  
Author(s):  
G. S. Seth ◽  
R. Tripathi ◽  
R. Sharma ◽  
A. J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Fluid Velocity ◽  
Convection Flow ◽  
Fluid Temperature ◽  
Inclined Plate ◽  
Natural Convection Flow ◽  
Species Concentration ◽  
Double Diffusive

AbstractAn investigation of unsteady MHD double diffusive natural convection flow of a viscous, incompressible, electrically conducting, heat absorbing, radiating and chemically-reactive fluid past an exponentially accelerated moving inclined plate in a fluid-saturated porous medium, when the temperature of the plate and the concentration at the surface of the plate have ramped profiles, is carried out. Exact solutions for the fluid velocity, fluid temperature and the species concentration, under Boussinesq approximation, are obtained in closed form by the Laplace transform technique. The expressions for the shear stress, rate of heat transfer and the rate of mass transfer at the plate are also derived. Numerical evaluations of the fluid velocity, fluid temperature and the species concentration are performed and displayed graphically whereas those of the shear stress, rate of heat transfer and the rate of mass transfer at the plate are presented in tabular form for various values of the pertinent flow parameters.

Natural Convection Flow in Vertical Channel Due to Ramped Wall Temperature at One Boundary

2009 ◽  
Author(s):  
Narahari Marneni ◽  
Vijay R. Raghavan
Keyword(s):  
Natural Convection ◽  
Volume Flow Rate ◽  
Vertical Channel ◽  
The Other ◽  
Temperature Fields ◽  
Convection Flow ◽  
Physical Parameters ◽  
Fluid Temperature ◽  
Laplace Transform Technique ◽  
The Laplace Transform

An exact solution to the problem of unsteady natural convective flow of a viscous and incompressible fluid in a vertical parallel plate channel due to ramp heating at one boundary is presented. The temperature at one of the channel plates increases linearly over a certain time period and then remains constant while that at the other plate is maintained at the initial fluid temperature. The Laplace transform technique has been used to obtain the expressions for the velocity and temperature fields by solving the dimensionless governing partial differential equations under appropriate boundary conditions. The influence of the physical parameters on the velocity field, the temperature field, rate of heat transfer, skin-friction and volume flow rate of the fluid are analyzed systematically. The shear stress at the plate with ramped temperature boundary condition is significantly higher than that at the other plate because of the steeper velocity profiles in the vicinity. The Nusselt number at the plate with ramped temperature is much higher than that at the other plate indicating that much of the energy released from the plate because of its increasing temperature with time is convected out by the fluid before it reaches the second plate. The natural convection due to ramp heating has also been compared with the baseline case of flow with constant temperature.

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.

MHD Double Diffusive Natural Convection Flow Over Exponentially Accelerated Inclined Plate

2016 ◽  
Vol 33 (1) ◽  
pp. 87-99 ◽  
Author(s):  
G. S. Seth ◽  
R. Tripathi ◽  
R. Sharma ◽  
A. J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Fluid Velocity ◽  
Convection Flow ◽  
Fluid Temperature ◽  
Inclined Plate ◽  
Natural Convection Flow ◽  
Species Concentration ◽  
Double Diffusive

AbstractAn investigation of unsteady MHD double diffusive natural convection flow of a viscous, incompressible, electrically conducting, heat absorbing, radiating and chemically-reactive fluid past an exponentially accelerated moving inclined plate in a fluid-saturated porous medium, when the temperature of the plate and the concentration at the surface of the plate have ramped profiles, is carried out. Exact solutions for the fluid velocity, fluid temperature and the species concentration, under Boussinesq approximation, are obtained in closed form by the Laplace transform technique. The expressions for the shear stress, rate of heat transfer and the rate of mass transfer at the plate are also derived. Numerical evaluations of the fluid velocity, fluid temperature and the species concentration are performed and displayed graphically whereas those of the shear stress, rate of heat transfer and the rate of mass transfer at the plate are presented in tabular form for various values of the pertinent flow parameters.

scholarly journals MHD natural convection flow of Casson fluid in an annular microchannel containing porous medium with heat generation/absorption

2020 ◽  
Vol 9 (1) ◽  
pp. 223-232 ◽  
Author(s):  
B.J. Gireesha ◽  
S. Sindhu
Keyword(s):  
Porous Medium ◽  
Natural Convection ◽  
Skin Friction ◽  
Interaction Parameter ◽  
Heat Generation ◽  
Velocity Slip ◽  
Casson Fluid ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Wall Interaction

AbstractThis study has been conducted to focus on natural convection flow of Casson fluid through an annular microchannel formed by two cylinders in the presence of magnetic field. The process of heat generation/absorption is taken into consideration. Combined effects of various parameters such as porous medium, velocity slip and temperature jump are considered. Solution of the present mathematical model is obtained numerically using fourth-fifth order Runge-Kutta-Fehlberg method. The flow velocity, thermal field, skin friction and Nusselt number are scrutinized with respect to the involved parameters of interest such as fluid wall interaction parameter, rarefaction parameter, Casson parameter and Darcy number with the aid of graphs. It is established that higher values of Casson parameter increases the skin friction coefficient. Further it is obtained that rate of heat transfer diminishes as fluid wall interaction parameter increases.

Natural convection flow in a vertical micro-annulus with time-periodic thermal boundary conditions

2018 ◽  
Vol 14 (5) ◽  
pp. 1064-1081
Author(s):  
Basant Kumar Jha ◽  
Michael O. Oni
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Skin Friction ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
The Impact ◽  
Time Periodic

PurposeThe purpose of this paper is to investigate the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.Design/methodology/approachAnalytical solution in terms of Bessel’s function and modified Bessel’s function of order 0 and 1 is obtained for velocity, temperature, Nusselt number, skin friction and mass flow rate.FindingsIt is established that the role of Knudsen number and fluid–wall interaction parameter is to decrease fluid temperature, velocity, Nusselt number and skin friction.Research limitations/implicationsNo laboratory practical or experiment was conducted.Practical implicationsCooling device in electronic panels, card and micro-chips is frequently cooled by natural convection.Originality/valueIn view of the amount of works done on natural convection in microchannel, it becomes interesting to investigate the effect that time-periodic heating has on natural convection flow in a vertical micro-annulus. The purpose of this paper is to examine the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.

MHD free convection flow in a vertical porous super-hydrophobic micro-channel

2020 ◽  
pp. 095440892096505
Author(s):  
BK Jha ◽  
BJ Gwandu
Keyword(s):  
Slip Surface ◽  
Hydrophobic Surface ◽  
Transverse Magnetic ◽  
Convection Flow ◽  
Fluid Temperature ◽  
Micro Channel ◽  
Channel One ◽  
Electrically Conducting ◽  
Micro Fluidics ◽  
Temperature Jump Coefficient

A free convective flow of an incompressible and electrically conducting fluid through a vertical micro-channel of rectangular geometry was considered. Both plates were porous and heated alternately. A transverse magnetic field was applied across the channel. One channel wall surface was no slip and the other was super-hydrophobic. The purpose of the study is to examine the effects of super-hydrophobicity, magnetism and wall porosity on the main characteristics of the flow. The exact solutions of the formulated differential equations were provided. A few highlights of the results obtained include: (1) the magnetic parameter lowered the skin friction at both surfaces when either of them were heated, (2) the suction/injection parameter raised the fluid temperature when the super-hydrophobic surface (SHS) was heated and brought it down when the no slip surface (NSS) was heated, (3) a critical temperature jump coefficient was observed at which the flow rates in both cases (only SHS heated, and only NSS heated) were equal. A few application areas of the research include micro-fluidics and micro-electronics.

RADIATION EFFECTS ON AN UNSTEADY NATURAL CONVECTIVE FLOW OF A NANOFLUID PAST AN INFINITE VERTICAL PLATE

NANO ◽  
2013 ◽  
Vol 08 (01) ◽  
pp. 1350001 ◽  
Author(s):  
P. LOGANATHAN ◽  
P. NIRMAL CHAND ◽  
P. GANESAN
Keyword(s):  
Heat Transfer ◽  
Skin Friction ◽  
Convective Flow ◽  
Radiation Effects ◽  
Vertical Plate ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Skin Friction Coefficient ◽  
Laplace Transform Technique ◽  
Infinite Vertical Plate

An exact analysis is carried out to study the radiation effects on an unsteady natural convective flow of a nanofluid past an impulsively started infinite vertical plate. The nanofluids containing nanoparticles of aluminium oxide, copper, titanium oxide and silver with nanoparticle volume fraction range less than or equal to 0.04 are considered. The partial differential equations governing the flow are solved by Laplace transform technique. The influence of various parameters on velocity and temperature profiles, as well as Nusselt number and skin-friction coefficient, are examined and presented graphically. An increase in radiation parameter and time leads to fall in temperature of the fluid. The presence of nanoparticles and thermal radiation increases the rate of heat transfer and skin friction. The effect of heat transfer is found to be more pronounced in silver water nanofluid than in the other nanofluids. It is observed that the fluid velocity increases with an increase in Grashof number and time. Excellent validation of the present results is achieved with existing results in the literature.

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