scholarly journals Thermal Radiation and MHD Effects in the Mixed Convection Flow of Fe3O4–Water Ferrofluid towards a Nonlinearly Moving Surface

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 95 ◽  
Author(s):  
Anuar Jamaludin ◽  
Kohilavani Naganthran ◽  
Roslinda Nazar ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Stability Analysis ◽  
Differential Equations ◽  
Mixed Convection ◽  
Thermal Radiation ◽  
Numerical Solutions ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Moving Surface ◽  
The Stability

This paper investigated the magnetohydrodynamic (MHD) mixed convection flow of Fe3O4-water ferrofluid over a nonlinearly moving surface. The present work focused on how the state of suction on the surface of the moving sheet and the effects of thermal radiation influence the fluid flow and heat transfer characteristics within the stagnation region. As such, a similarity solution is engaged to transform the governing partial differential equations to the ordinary differential equations. A collocation method, namely the bvp4c function in the MATLAB software solves the reduced system, numerically. Two different numerical solutions were identified for the cases of assisting and opposing flows. The stability analysis was conducted to test the stability of the non-uniqueness solutions. The increment of the thermal radiation effect affects the rate of heat transfer to decrease. The stability analysis conveyed that the upper branch solution is stable and vice versa for the other solution.

scholarly journals Effects of Thermal Radiation on Mixed Convection Flow of a Micropolar Fluid from an Unsteady Stretching Surface with Viscous Dissipation and Heat Generation/Absorption

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Khilap Singh ◽  
Manoj Kumar
Keyword(s):  
Mixed Convection ◽  
Thermal Radiation ◽  
Heat Generation ◽  
Micropolar Fluid ◽  
Numerical Solutions ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Stretching Surface ◽  
Local Skin ◽  
Unsteady Mixed Convection

A numerical model is developed to examine the effects of thermal radiation on unsteady mixed convection flow of a viscous dissipating incompressible micropolar fluid adjacent to a heated vertical stretching surface in the presence of the buoyancy force and heat generation/absorption. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The model contains nonlinear coupled partial differential equations which have been converted into ordinary differential equation by using the similarity transformations. The dimensionless governing equations for this investigation are solved by Runge-Kutta-Fehlberg fourth fifth-order method with shooting technique. Numerical solutions are then obtained and investigated in detail for different interesting parameters such as the local skin-friction coefficient, wall couple stress, and Nusselt number as well as other parametric values such as the velocity, angular velocity, and temperature.

Unsteady mixed convection flow at a three-dimensional stagnation point

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amin Noor ◽  
Roslinda Nazar ◽  
Kohilavani Naganthran ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Mixed Convection ◽  
Stagnation Point ◽  
Three Dimensional ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Unsteady Mixed Convection

Purpose This paper aims to probe the problem of an unsteady mixed convection stagnation point flow and heat transfer past a stationary surface in an incompressible viscous fluid numerically. Design/methodology/approach The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, which is then solved numerically by a Runge – Kutta – Fehlberg method with shooting technique and a collocation method, namely, the bvp4c function. Findings The effects of the governing parameters on the fluid flow and heat transfer characteristics are illustrated in tables and figures. It is found that dual (upper and lower branch) solutions exist for both the cases of assisting and opposing flow situations. A stability analysis has also been conducted to determine the physical meaning and stability of the dual solutions. Practical implications This theoretical study is significantly relevant to the applications of the heat exchangers placed in a low-velocity environment and electronic devices cooled by fans. Originality/value The case of suction on unsteady mixed convection flow at a three-dimensional stagnation point has not been studied before; hence, all generated numerical results are claimed to be novel.

scholarly journals Thermal radiation and magnetic field effects on unsteady mixed convection flow and mass transfer over a porous stretching surface with heat generation

2013 ◽  
Vol 18 (4) ◽  
pp. 1151-1164 ◽  
Author(s):  
G.V.R. Reddy ◽  
B.A. Reddy ◽  
N.B. Reddy
Keyword(s):  
Mass Transfer ◽  
Differential Equations ◽  
Mixed Convection ◽  
Thermal Radiation ◽  
Heat Generation ◽  
Convection Flow ◽  
Physical Parameters ◽  
Mixed Convection Flow ◽  
Stretching Surface ◽  
Porous Stretching Surface

Abstract The effects of thermal radiation and mass transfer on an unsteady hydromagnetic boundary layer mixed convection flow along a vertical porous stretching surface with heat generation are studied. The fluid is assumed to be viscous and incompressible. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity variables. Numerical solutions of these equations are obtained by using the Runge-Kutta fourth order method along with the shooting technique. Velocity, temperature, concentration, the skin-friction coefficient, Nusselt number and Sherwood number for variations in the governing thermo physical parameters are computed, analyzed and discussed.

Influence of Thermal Radiation on the Unsteady Mixed Convection Flow of a Jeffrey Fluid over a Stretching Sheet

2010 ◽  
Vol 65 (8-9) ◽  
pp. 711-719 ◽  
Author(s):  
Tasawar Hayat ◽  
Meraj Mustafa
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Thermal Radiation ◽  
Deborah Number ◽  
Convection Flow ◽  
Jeffrey Fluid ◽  
Mixed Convection Flow ◽  
Suction Parameter ◽  
Unsteady Mixed Convection ◽  
Homotopy Analysis

This study is concerned with the effect of thermal radiation on the unsteady mixed convection flow of a Jeffrey fluid past a porous vertical stretching surface. The arising problems of flow and heat transfer are solved analytically by employing homotopy analysis method (HAM). It is observed that the flow field is influenced appreciably by the unsteadiness parameter ζ , suction parameter S, mixed convection parameter λ , Deborah number β , Prandtl number Pr, and the radiation parameter Nr. Our performed computations depict that the heat transfer rate is increased with increasing values of Pr, Nr, and ζ

scholarly journals Effect of gravity modulation on mixed convection flow of second grade fluid with different shapes of nanoparticles

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Noraihan Afiqah Rawi ◽  
Mohd Rijal Ilias ◽  
Zaiton Mat Isa ◽  
Sharidan Shafie
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Mixed Convection ◽  
Second Grade ◽  
Convection Flow ◽  
Gravity Modulation ◽  
Mixed Convection Flow ◽  
Second Grade Fluid ◽  
Grade Fluid ◽  
Different Shapes

The problem of unsteady mixed convection flow of second grade fluid over an inclined stretching plate under the influence of different shapes of nanoparticles is studied in this paper. The influence of gravity modulation is also considered. Carboxymethyl cellulose solution (CMC) is chosen as the non-Newtonian base fluid. Based on Tiwari-Das nanofluid model, the governing partial differential equations are transformed into a system of ordinary differential equations and solved numerically using an implicit finite difference scheme. The effect of different shapes and volume fraction of solid nanoparticles on the enhancement of convective heat transfer of second grade nanofluid associated with the effect amplitude of modulation, frequency of oscillation, and material parameter is discussed in details. The results indicated that, the needle-shaped nanoparticles give the highest enhancement on the heat transfer of second grade nanofluid compared to sphere and disk-shaped nanoparticles.

Mixed Convection Flow of a Micropolar Fluid Past a Vertical Stretching Surface in a Thermally Stratified Porous Medium with Thermal Radiation

2013 ◽  
Vol 29 (3) ◽  
pp. 461-470 ◽  
Author(s):  
Mostafa A.A. Mahmoud ◽  
Shimaa E. Waheed
Keyword(s):  
Porous Medium ◽  
Differential Equations ◽  
Mixed Convection ◽  
Thermal Radiation ◽  
Ordinary Differential Equations ◽  
Micropolar Fluid ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Linear Ordinary Differential Equations ◽  
Permeability Parameter

AbstractThis paper is concerned with the effect of thermally stratification on the steady, two-dimensional mixed convection flow of a micropolar fluid past a vertical stretching permeable surface saturated in porous medium taking into account the effect of thermal radiation. The governing system of partial differential equations describing the problem are converted into a system of non-linear ordinary differential equations using similarity transformation. The resulting system of coupled nonlinear ordinary differential equations is solved numerically using the Chebyshev spectral method. The numerical results for the velocity, the micro-rotation and the temperature are displayed graphically showing the effects of various parameters like the buoyancy parameter, the radiation parameter, the stratification parameter, the permeability parameter and the suction/injection parameter. Moreover, the numerical values of the local skinfriction coefficient, the wall couple stress and the local Nusselt number for these parameters are also tabulated and discussed.

Mixed convection flow of a hybrid nanofluid past a vertical wedge with thermal radiation effect

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Natalia C. Roșca ◽  
Alin V. Roșca ◽  
Ioan Pop
Keyword(s):  
Differential Equations ◽  
Mixed Convection ◽  
Thermal Radiation ◽  
Radiation Effect ◽  
Convection Flow ◽  
Hybrid Nanofluid ◽  
Mixed Convection Flow ◽  
Content Type ◽  
Thermal Radiation Effect ◽  
Vertical Wedge

Purpose The purpose of this paper is to numerically study the problem of mixed convection flow of a hybrid nanofluid past a vertical wedge with thermal radiation effect. Design/methodology/approach The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, which is then solved numerically through the function bvp4c from MATLAB for different values of the governing parameters. The solutions contain a mixed convection parameter λ that has a considerable impact on the flow fields. Findings It is found that the solutions of the ordinary (similarity) differential equations have two branches, upper and lower branch solutions, in a certain range of the mixed convection and several other parameters. To establish which of these solutions are stable and which are not, a stability analysis has been performed. The effects of the governing parameters on the fluid flow and heat transfer characteristics are illustrated in tables and figures. It is found that dual (upper and lower branch) solutions exist for both the cases of assisting and opposing flow situations. A stability analysis has also been conducted to determine the physical meaning and stability of the dual solutions. Practical implications This theoretical study is significantly relevant to the applications of the heat exchangers placed in a low-velocity environment and electronic devices cooled by fans. Originality/value The case of mixed convection flow of a hybrid nanofluid past a vertical wedge with thermal radiation effects has not been studied before, and hence all generated numerical results are claimed to be original and novel.

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