Thermal aspects of Oldroyd-B nanofluid over accelerated surface with variable thermal conductivity and modified diffusion theories

2021 ◽  
pp. 2150185
Author(s):  
Samaira Aziz ◽  
Iftikhar Ahmad ◽  
Sami Ullah Khan ◽  
Nasir Ali
Keyword(s):  
Thermal Conductivity ◽  
Concentration Profile ◽  
Heated Surface ◽  
Variable Thermal Conductivity ◽  
Physical Parameters ◽  
Rheological Analysis ◽  
Heating Systems ◽  
Boundary Layer Equations ◽  
Relaxation Parameters ◽  
Thermal Sciences

The growing interest in emerging nanotechnologies has led the scientists towards to investigate the interaction of nanoparticles with fluids. Current continuation endeavors the rheological analysis for the Oldroyd-B nanomaterial across periodically accelerated and heated surface. The interesting features of thermophoresis and Brownian motions are presented by following famous Buongiorno nanofluid model. Further, Cattaneo–Christov heat and mass flux expressions are exploited to determine the characteristics of thermal and mass diffusions. As a novelty, the variable thermal conductivity and heat absorption/generation consequences are also utilizing the energy equation. The flow model has been developed by using concerning boundary layer equations which are converted into dimensionless forms by using appropriate variables. The analytical solution of such transmuted equations is computed by using homotopy analytic method. Various physical parameters of interest are scrutinized through various graphs. The observations from analysis convey a declining change in nanofluid concentration and temperature with variation of thermal and solutal relaxation parameters, respectively. Moreover, thermophoresis parameter causes an enhancement of concentration profile while a retarded concentration profile results with increment of Schmidt number. The obtained theoretical results reflect significant applications in cooling and heating systems, thermal sciences, manufacturing processes, extrusion systems, enhancement of transport of energy and heat resources.

Effect of Variable Thermal Conductivity Calibration Functions on Fin Temperature Distribution

2019 ◽  
Vol 393 ◽  
pp. 47-58 ◽  
Author(s):  
Partner Luyanda Ndlovu ◽  
Raseelo Joel Moitsheki
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Variational Iteration Method ◽  
Variable Thermal Conductivity ◽  
Solution Technique ◽  
Physical Parameters ◽  
Calibration Function ◽  
Shooting Technique ◽  
Extended Surfaces ◽  
Fourth Order Method

In this article, we introduce a new thermal conductivity calibration function in modeling heat transfer through extended surfaces. The variable thermal conductivity functions are studied on a stand alone basis and further compared to one another. The calculations are carried out using the Variational Iteration Method (VIM) which is an analytical solution technique. The series solutions are bench-marked against the numerical results obtained by applying the Runge-Kutta fourth order method coupled with shooting technique. The effects of some physical parameters such as the thermogeometric fin parameter and thermal conductivity gradient, on temperature distribution are illustrated and explained.

scholarly journals Thermo diffusion aspects in Jeffrey nanofluid over periodically moving surface with time dependent thermal conductivity

2019 ◽  
pp. 312-312 ◽  
Author(s):  
Khan Ullah ◽  
Shehzad Ali ◽  
Abbasi Munir ◽  
Arshad Hussain
Keyword(s):  
Thermal Conductivity ◽  
Nonlinear Differential Equations ◽  
Heated Surface ◽  
Lewis Number ◽  
Double Diffusion ◽  
Variable Thermal Conductivity ◽  
Deborah Number ◽  
Time Dependent ◽  
Jeffrey Fluid ◽  
Homotopy Analysis

Double diffusion flow of Jeffrey fluid in presence of nanoparticles is studied theoretically under time dependent thermal conductivity. The considered nanoparticles are evaporated over convectively heated surface which moves periodically in its own plane. The appropriate dimensionless variables are employed to obtain the dimensionless forms of governing equations. We computed the analytical solution of nonlinear differential equations by utilizing homotopy analysis method. The present investigation reveals the features of various emerging parameters like Deborah number, combined parameter, oscillation frequency to stretching rate ratio, Prandtl number, Lewis number, thermophoresis parameter, Brownian motion parameter, nano Lewis number, modified Dufour parameter and Dufour solutal Lewis number. A useful enhancement in movement of nanoparticles is observed by utilizing the combined magnetic and porosity effects. Unlike traditional studies, present analysis is confined with the unsteady transportation phenomenon from periodically moving surfaces. Such computation may be attributable in flow results from tensional vibrations due to stretching and elastic surfaces. The simulation presented here can be attractable significance in the bioengineered nanoparticles manufacturing. It is observed that the heat transportation of nanoparticles may efficiently enhance through the utilization of variable thermal conductivity. The solutal concentration decreases with increasing Deborah number and Lewis number. It is further noted that the nano Lewis number causes reduction of nanoparticles concentration.

On Heat Transfer of a Two-Step Radiating Slab of Variable Thermal Conductivity

2020 ◽  
Vol 987 ◽  
pp. 137-141
Author(s):  
Ramoshweu Solomon Lebelo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Chemical Reaction ◽  
Combustion Process ◽  
Variable Thermal Conductivity ◽  
Nonlinear Ordinary Differential Equation ◽  
Physical Parameters ◽  
Exothermic Chemical Reaction ◽  
Temperature Levels ◽  
Heat Transfers

An investigation of heat transfers in a combustible stockpile whose materials are of variable thermal conductivity is conducted in this article. The stockpile is modeled in rectangular slap and a two-step exothermic chemical reaction responsible for the combustion process is assumed. The reactive slab is also assumed to lose heat to the ambient by radiation. The Runge-Kutta Fehlberg (RKF45) method coupled with the Shooting technique is applied to tackle numerically the nonlinear ordinary differential equation (ODE) governing the problem. The process of heat transfer during combustion is made easy to understand by investigating effects of selected thermo-physical parameters on the system’s temperature. The results show that some thermo-physical parameters accelerate the exothermic chemical reaction and therefore raise the temperature levels, and that others help to reduce heat release rate to lower the temperature profiles. The graphs for the results are plotted and discussed accordingly.

Instability of Variable Thermal Conductivity Magnetohydrodynamic Nanofluid Flow in a Vertical Porous Channel of Varying Width

2017 ◽  
Vol 378 ◽  
pp. 85-101
Author(s):  
Md. Sarwar Alam ◽  
Oluwole Daniel Makinde ◽  
Md. Abdul Hakim Khan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Differential Equations ◽  
Entropy Generation ◽  
Fluid Velocity ◽  
Nonlinear Partial Differential Equations ◽  
Vertical Channel ◽  
Porous Wall ◽  
Variable Thermal Conductivity ◽  
Physical Parameters

A numerical investigation is performed into the heat transfer and entropy generation of a variable thermal conductivity magnetohydrodynamic flow of Al2O3-water nanofluid in a vertical channel of varying width with right porous wall, which enable the fluid to enter. The effects of the Lorentz force, buoyancy force, viscous dissipation and Joule heating are considered and modeled using the transverse momentum and energy balance equations respectively. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations using appropriate similarity transformations and then solved numerically using power series with Hermite-Padé approximation method. A stability analysis has been performed for the local rate of shear stress and Nusselt number that indicates the existence of dual solution branches. Numerical results are achieved for the fluid velocity, temperature as well as the rate of heat transfer at the wall and the entropy generation of the system. The present results are original and new for the flow and heat transfer past a channel of varying width in a nanofluid which shows that the physical parameters have significant effects on the flow field.

scholarly journals Impact of Temperature-Dependent Heat Source/Sink and Variable Species Diffusivity on Radiative Reiner–Philippoff Fluid

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
T. Sajid ◽  
M. Sagheer ◽  
S. Hussain
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Transfer ◽  
Heat Source ◽  
Transfer Rate ◽  
Variable Thermal Conductivity ◽  
Physical Parameters ◽  
Molecular Diffusivity ◽  
Source Sink ◽  
The Impact

The principle aim of the current communication is to scrutinize the impact of distinguished effects like variable thermal conductivity and variable molecular diffusivity on non-Newtonian Reiner–Philippoff fluid moving over a stretchable surface. The process of heat transfer is carried out in the presence of nonlinear thermal radiation, variable thermal conductivity, and heat generation/absorption. Furthermore, the study of mass transfer phenomena is carried out in the existence of variable molecular diffusivity. The PDEs regarding our model are renovated into ODEs by utilizing similarity transformation. Furthermore, the dimensionless model is tackled with the help of the RK4 method in conjunction with the shooting technique. The effects of different physical parameters that emerged during the numerical simulation on mass transfer rate, heat transfer rate, and velocity field are portrayed in the form of tables and graphs. It is noteworthy that an elevation in the heat source/sink parameters causes a reduction in the temperature profile. Moreover, a positive variation in the species diffusivity parameter augments the mass fraction field. A variation in the fluid parameter is found to be significantly affecting the shear thinning and shear thickening behaviour of the fluid. Reliability of the numerical outcomes is judged by comparing the obtained outcomes with the already available literature. The article is unique in its sense that the heat and mass transfer analysis of Reiner–Philippoff fluid under the aforementioned effects has not been investigated yet.

Flow and Heat Transfer of Powell–Eyring Fluid due to an Exponential Stretching Sheet with Heat Flux and Variable Thermal Conductivity

2015 ◽  
Vol 70 (3) ◽  
pp. 163-169 ◽  
Author(s):  
Ahmed M. Megahed
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Differential Equations ◽  
Variable Thermal Conductivity ◽  
Physical Parameters ◽  
Flow And Heat Transfer ◽  
Non Linear ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter

AbstractAn analysis was carried out to describe the problem of flow and heat transfer of Powell–Eyring fluid in boundary layers on an exponentially stretching continuous permeable surface with an exponential temperature distribution in the presence of heat flux and variable thermal conductivity. The governing partial differential equations describing the problem were transformed into a set of coupled non-linear ordinary differential equations and then solved with a numerical technique using appropriate boundary conditions for various physical parameters. The numerical solution for the governing non-linear boundary value problem is based on applying the shooting method over the entire range of physical parameters. The effects of various parameters like the thermal conductivity parameter, suction parameter, dimensionless Powell–Eyring parameters and the Prandtl number on the flow and temperature profiles as well as on the local skin-friction coefficient and the local Nusselt number are presented and discussed. In this work, special attention was given to investigate the effect of the thermal conductivity parameter on the velocity and temperature fields above the sheet in the presence of heat flux. The numerical results were also validated with results from a previously published work on various special cases of the problem, and good agreements were seen.

Change in conductivity of magnetohydrodynamic Darcy–Forchheimer second-grade fluid flow due to variable thickness surface

2019 ◽  
Vol 97 (8) ◽  
pp. 809-815 ◽  
Author(s):  
A. Haider ◽  
T. Salahuddin ◽  
M.Y. Malik
Keyword(s):  
Thermal Conductivity ◽  
Fluid Flow ◽  
Differential Equations ◽  
Variable Thermal Conductivity ◽  
Second Grade ◽  
Physical Parameters ◽  
Second Grade Fluid ◽  
Inertia Coefficient ◽  
Grade Fluid ◽  
Energy And Momentum

The current investigation is communicated to analyze the characteristics of Darcy–Forchheimer second-grade fluid flow enclosed by a deformable sheet in the existence of both variable thermal conductivity and magnetohydrodynamics. The leading nonlinear energy and momentum partial differential equations are converted into nonlinear ordinary differential equations by utilizing suitable analogous approach. Then the acquired nonlinear problem is numerically calculated by utilizing BVP4C (built in) technique in MATLAB. The influence of certain appropriate physical parameters, namely wall thickness, second-grade fluid, Hartmann number, power index, porosity parameter, inertia coefficient, Prandtl number, and thermal conductivity, on temperature and velocity is studied and deliberated in detail. Numerical calculations of Nusselt number and skin friction for distinct estimations of appearing parameters are analysed through graphs and tables.

Numerical Solution of Sisko Fluid Over a Stretching Cylinder and Heat Transfer with Variable Thermal Conductivity

2016 ◽  
Vol 32 (5) ◽  
pp. 593-601 ◽  
Author(s):  
M.Y. Malik ◽  
A. Hussain ◽  
T. Salahuddin ◽  
M. Awais ◽  
S. Bilal
Keyword(s):  
Thermal Conductivity ◽  
Differential Equations ◽  
Numerical Solution ◽  
Numerical Study ◽  
Fluid Model ◽  
Variable Thermal Conductivity ◽  
Physical Parameters ◽  
Heat Equations ◽  
Stretching Cylinder ◽  
Sisko Fluid

AbstractPresent paper addresses the numerical study of Sisko fluid model over stretching cylinder with variable thermal conductivity. The governing equations are simplified by incorporating the boundary layer approximations. After employing suitable similarity transformations partial differential equations are reduced to ordinary differential equations. To obtain numerical solution shooting method in conjunction with Runge-Kutta-Fehlberg method is used. For the analysis of model, variations due to different physical parameters involved in momentum and heat equations are reflected through graphs. Also, the effects of physical parameters on skin-friction coefficient and Nusselt number are represented through graphs as well as tables.

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