Entropy generation and thermo-diffusion effects on unsteady chemically reactive slip flow between two rotating disks

2019 ◽  
Vol 29 (10) ◽  
pp. 3795-3821
Author(s):  
Sumaira Qayyum ◽  
Muhammad Ijaz Khan ◽  
Tasawar Hayat ◽  
Ahmed Alsaedi
Keyword(s):  
Magnetic Field ◽  
Entropy Generation ◽  
Stokes Equations ◽  
Tangential Velocity ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Thermal Equation ◽  
Content Type ◽  
Flow Variables

Purpose The purpose of this study is to analyze the Entropy generation analysis and heat transport in three-dimensional flow between two stretchable disks. Joule heating and heat generation/absorption are incorporated in the thermal equation. Thermo-diffusion effect is also considered. Flow is conducting for time-dependent applied magnetic field. Induced magnetic field is not taken into consideration. Velocity and thermal slip conditions at both the disks are implemented. The flow problem is modeled by using Navier–Stokes equations with entropy generation rate and Bejan number. Design/methodology/approach Von Karman transformations are used to reduce the nonlinear governing expressions into an ordinary one and then tackled by homotopy analysis method for convergent series solutions. The nonlinear expressions for total entropy generation rate are obtained with appropriate transformations. The impacts of different flow variables on velocity, temperature, entropy generation rate and Bejan number are described graphically. Velocity, temperature and concentration gradients are discussed in the presence of flow variables. Findings Axial, radial and tangential velocity profiles show decreasing trend for larger values of velocity slip parameters. For a larger Brinkman number, the entropy generation increases, while a decreasing trend is noticed for Bejan number. Originality/value To the best of the authors’ knowledge, no such analyses have been reported in the literature.

Entropy analysis of Poiseuille nanofluid flow in a porous channel with slip and convective boundary conditions under magnetic field

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
S. Das ◽  
S. Chakraborty ◽  
R. N. Jana
Keyword(s):  
Magnetic Field ◽  
Entropy Generation ◽  
Poiseuille Flow ◽  
Magnetic Parameter ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Convective Heating ◽  
Bejan Number ◽  
Content Type ◽  
Hydrodynamic Slip

Purpose This study aims to expose the flow phenomena and entropy generation during a; magnetohydrodynamic (MHD) Poiseuille flow of water-based nanofluids (NFs) in a porous channel subject to hydrodynamic slip and convective heating boundary conditions. The flow caused by the uniform pressure; gradient between infinite parallel plates is considered steady and fully developed. The nanoparticles; namely, copper, alumina and titanium oxide are taken with pure water as the base fluid. Viscous dissipation and Joule heating impacts are also incorporated in this investigation. Design/methodology/approach The reduced governing equations are solved analytically in closed form. The physical insights of noteworthy parameters on the important flow quantities are demonstrated through graphs and analyzed elaborately. The thermodynamic analysis is performed by calculating entropy generation; rate and Bejan number. A graphical comparison between solutions corresponding to NFs and regular fluid in the channel is also provided. Findings The analysis of the results divulges that entropy generation minimization can be achieved by an appropriate combination of the geometrical and physical parameters of thermomechanical systems. It is reported that ascent in magnetic parameter number declines the velocity profiles, while the inverse pattern is witnessed with augmentation in hydrodynamic slip parameters. The temperature dissemination declines with the growth of Biot numbers. It is perceived that the entropy generation rate lessens with an upgrade in magnetic parameter, whereas the reverse trend of Bejan number is perceived with expansion in magnetic parameter and Biot number. The important contribution of the result is that the entropy generation rate is controlled with an appropriate composition of thermo-physical parameter values. Moreover, in the presence of a magnetic field and suction/injection at the channel walls, the shear stresses at the channel walls are reduced about two times. Practical implications In various industrial applications, minimizing entropy generation plays a significant role. Miniaturization of entropy is the utilization of the energy of thermal devices such as micro heat exchangers, micromixers, micropumps and cooling microelectromechanical devices. Originality/value An attentive review of the literature discloses that quite a few studies have been conducted on entropy generation analysis of a fully developed MHD Poiseuille flow of NFs through a permeable channel subject to the velocity slip and convective heating conditions at the walls.

Entropy generation in radiative flow of Ree-Eyring fluid due to due rotating disks

2019 ◽  
Vol 29 (6) ◽  
pp. 2057-2079 ◽  
Author(s):  
Muhammad Ijaz Khan ◽  
Sohail Ahmad Khan ◽  
Tasawar Hayat ◽  
Muhammad Faisal Javed ◽  
Ahmed Alsaedi
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Magnetic Parameter ◽  
Nonlinear Flow ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Rotating Disks ◽  
Content Type ◽  
The Impact

Purpose This study aims to examine the flow characteristics of Ree–Eyring fluid between two rotating disks. The characteristics of heat transfer are discussed in presence of viscous dissipation, heat source/sink and nonlinear radiative heat flux. Design/methodology/approach Nonlinear flow expressions lead to ordinary ones through adequate similarity transformations. The ordinary differential system has been tackled through optimal homotopic method. The impact of different flow variables on the velocity field, entropy generation rate and temperature fields is graphically discussed. The surface drag force and heat transfer rate are numerically examined via various pertinent parameters. Findings By minimization of values of stretching parameter and Brinkman number, the entropy generation rate can be controlled. The entropy generation rate enhances for higher values of magnetic parameter, while the Bejan number is decreased via magnetic parameter. Originality/value No such work is yet published in the literature.

Analysis of entropy generation in an inclined channel flow containing two immiscible micropolar fluids using HAM

2016 ◽  
Vol 26 (3/4) ◽  
pp. 1027-1049 ◽  
Author(s):  
J. Srinivas ◽  
J.V. Ramana Murthy ◽  
Ali J Chamkha
Keyword(s):  
Entropy Generation ◽  
Flow Region ◽  
Flow Equation ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Micropolar Fluids ◽  
Content Type ◽  
Inclined Channel ◽  
Homotopy Analysis

Purpose – The purpose of this paper is to examine the flow, heat transfer and entropy generation characteristics for an inclined channel of two immiscible micropolar fluids. Design/methodology/approach – The flow region consists of two zones, the flow of the heavier fluid taking place in the lower zone. The flow is assumed to be governed by Eringen’s micropolar fluid flow equation. The resulting governing equations are then solved using the homotopy analysis method. Findings – The following findings are concluded: first, the entropy generation rate is more near the plates in both the zones as compared to that of the interface. This indicates that the friction due to surface on the fluids increases entropy generation rate. Second, the entropy generation rate is more near the plate in Zone I than that of Zone II. This may be due to the fact that the fluid in Zone I is more viscous. This indicates the more the viscosity of the fluid is, the more the entropy generation. Third, Bejan number is the maximum at the interface of the fluids. This indicates that the amount of exergy (available energy) is maximum and irreversibility is minimized at the interface between the fluids. Fourth, as micropolarity increases, entropy generation rate near the plates decreases and irreversibility decreases. This indicates an important industrial application for micropolar fluids to use them as a good lubricant. Originality/value – The problem is original as no work has been reported on entropy generation in an inclined channel with two immiscible micropolar fluids.

Thermodynamics Analysis of Unsteady MHD Mixed Convection with Slip and Thermal Radiation over a Permeable Surface

2017 ◽  
Vol 374 ◽  
pp. 29-46 ◽  
Author(s):  
Ahmad Muhammad ◽  
Oluwole Daniel Makinde
Keyword(s):  
Magnetic Field ◽  
Differential Equations ◽  
Thermal Radiation ◽  
Entropy Generation ◽  
Temperature Jump ◽  
Velocity Slip ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Local Similarity

This paper discusses the thermodynamics irreversibility in an unsteady hydromagnetic mixed convective flow of an electrically conducting optically dense fluid over a permeable vertical surface under the combined influence of thermal radiation, velocity slip, temperature jump, buoyancy force, viscous dissipation, Joule heating and magnetic field. The governing partial differential equations are reduced to ordinary differential equations by using similarity variable. A local similarity solution is obtained numerically using shooting technique coupled with Runge-Kutta Fehlberg integration method. The influence of various thermophysical parameters on velocity and temperature profiles, skin friction, Nusselt number, entropy generation rate and Bejan number are presented graphically and discussed quantitatively. It is found that velocity slip, surface injection and temperature jump can successfully reduce entropy generation rate in the presence of an applied magnetic field. A comparison of numerical solution is made with the exact solution under a special case scenario and excellent agreement is found.

MHD Mixed Convection Slip Flow of Radiating Casson Fluid with Entropy Generation in a Channel Filled with Porous Media

2017 ◽  
Vol 374 ◽  
pp. 47-66 ◽  
Author(s):  
Adetayo Samuel Eegunjobi ◽  
Oluwole Daniel Makinde
Keyword(s):  
Magnetic Field ◽  
Entropy Generation ◽  
Vertical Channel ◽  
Casson Fluid ◽  
Generation Rate ◽  
Radiation Absorption ◽  
Entropy Generation Rate ◽  
Integration Scheme ◽  
Bejan Number ◽  
Medium Permeability

In this paper, both first and second laws of thermodynamics are employed to investigate the combined effects of magnetic field, buoyancy force, velocity slip, suction/injection, porous medium permeability, thermal radiation absorption, viscous and Joule heating on mixed convective flow of an electrical conducting Casson fluid in a vertical channel. The dimensionless governing equations are obtained and solved numerically using a shooting technique coupled with a fourth order Runge-Kutta-Fehlberg integration scheme. The influence of various thermophysical parameters on velocity and temperature profiles, skin friction, Nusselt number, entropy generation rate and Bejan number are presented graphically and discussed quantitatively. It is found that with appropriate combination of thermophysical parameter values the entropy generation rate in the presence of an applied magnetic field can successfully.

scholarly journals MHD FLOW OF A REACTING AND RADIATING NANOLIQUID PAST AN INCLINED HEATED PERMEABLE PLATE: ANALYSIS OF ENTROPY GENERATION

2021 ◽  
Vol 51 (4) ◽  
pp. 269-276
Author(s):  
Oluwole Daniel Makinde ◽  
Adetayo Samuel Eegunjobi
Keyword(s):  
Magnetic Field ◽  
Entropy Generation ◽  
Variable Viscosity ◽  
Mhd Flow ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Integration Scheme ◽  
Bejan Number ◽  
Two Phase ◽  
Permeable Plate

This paper examines the aggregate impacts of magnetic field, thermophoresis, Brownian motion, variable viscosity, chemical reaction and radiative heat flux on the thermal putrefaction and immanent irreversibility of a channelling nanoliquid film flowing along with a slanted heated permeable plate. Following Buongiorno approach, the two-phase nanoliquid nonlinear model is obtained and addressed numerically using shooting technique as well as the Runge-Kutta- Fehlberg integration scheme. Effects of various emerging parameters on the overall flow structure with heat and mass transfer characteristics including entropy generation rate and Bejan number are displayed using diagrams and discussed. It is found that the entropy generation rate lessened with an upsurge in a magnetic field but heightened with an elevation in the buoyancy forces.

Numerical Investigation of Local Entropy Generation for Laminar Flow in Rotating-Disk Systems

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Mohammad Shanbghazani ◽  
Vahid Heidarpoor ◽  
Marc A. Rosen ◽  
Iraj Mirzaee
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Entropy Generation ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Local Entropy ◽  
Fluid Friction ◽  
Local Entropy Generation

The entropy generation is investigated numerically in axisymmetric, steady-state, and incompressible laminar flow in a rotating single free disk. The finite-volume method is used for solving the momentum and energy equations needed for the determination of the entropy generation due to heat transfer and fluid friction. The numerical model is validated by comparing it to previously reported analytical and experimental data for momentum and energy. Results are presented in terms of velocity distribution, temperature, local entropy generation rate, Bejan number, and irreversibility ratio distribution for various rotational Reynolds number and physical cases, using dimensionless parameters. It is demonstrated that increasing rotational Reynolds number increases the local entropy generation rate and irreversibility rate, and that the irreversibility is mainly due to heat transfer while the irreversibility associated with fluid friction is minor.

Modeling heat transfer of nanofluid flow in microchannels with electrokinetic and slippery effects using Buongiorno’s model

2019 ◽  
Vol 29 (8) ◽  
pp. 2566-2587 ◽  
Author(s):  
Hang Xu ◽  
Huang Huang ◽  
Xiao-Hang Xu ◽  
Qiang Sun
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Slip Length ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Lower Wall ◽  
Volumetric Concentration ◽  
Nanofluid Flow ◽  
Cross Sectional ◽  
Content Type

PurposeThis paper aims to study the heat transfer of nanofluid flow driven by the move of channel walls in a microchannel under the effects of the electrical double layer and slippery properties of channel walls. The distributions of velocity, temperature and nanoparticle volumetric concentration are analyzed under different slip-length. Also, the variation rates of flow velocity, temperature, concentration of nanoparticle, the pressure constant, the local volumetric entropy generation rate and the total cross-sectional entropy generation are analyzed.Design/methodology/approachA recently developed model is chosen which is robust and reasonable from the point of view of physics, as it does not impose nonphysical boundary conditions, for instance, the zero electrical potential in the middle plane of the channel or the artificial pressure constant. The governing equations of flow motion, energy, electrical double layer and stream potential are derived with slip boundary condition presented. The model is non-dimensionalized and solved by using the homotopy analysis method.FindingsSlip-length has significant influences on the velocity, temperature and nanoparticle volumetric concentration of the nanofluid. It also has strong effects on the pressure constant. With the increase of the slip-length, the pressure constant of the nanofluid in the horizontal microchannel decreases. Both the local volumetric entropy generation rate and total cross-sectional entropy generation rate are significantly affected by both the slip-length of the lower wall and the thermal diffusion. The local volumetric entropy generation rate at the upper wall is always higher than that around the lower wall. Also, the larger the slip-length is, the lower the total cross-sectional entropy generation rate is when the thermal diffusion is moderate.Originality/valueThe findings in this work on the heat transfer and flow phenomena of the nanofluid in microchannel are expected to make a contribution to guide the design of micro-electro-mechanical systems.

Thermodynamic Analysis of Magnetohydrodynamic Third Grade Fluid Flow with Variable Properties

2021 ◽  
Vol 55 ◽  
pp. 28-46
Author(s):  
Kgomotshwana Frans Thosago ◽  
Lazarus Rundora ◽  
Samuel Olumide Adesanya
Keyword(s):  
Fluid Flow ◽  
Thermodynamic Analysis ◽  
Entropy Generation ◽  
Generation Rate ◽  
Third Grade ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Third Grade Fluid ◽  
Entropy Generation Minimization ◽  
Grade Fluid

This article aims to computationally study entropy generation in a magnetohydrodynamic (MHD) third grade fluid flow in a horizontal channel with impermeable walls. The fluids viscosity and thermal conductivity are assumed to be dependent on temperature. The flow is driven by an applied uniform axial pressure gradient between infinite parallel plates and is considered to be incompressible, steady and fully developed. Adomian decomposition method (ADM) is used to obtain series solutions of the nonlinear governing equations. Thermodynamic analysis is done by computing the entropy generation rate and the irreversibility ratio (Bejan number). The effects of the various pertinent embedded parameters on the velocity field, temperature field, entropy generation rate and Bejan number are analysed through vivid graphical manipulations. The analysis shows that an appropriate combination of thermophysical parameters efficiently achieves entropy generation minimization in the thermomechanical system. The analysis shows that entropy generation minimization is achieved by increasing the magnetic field and the third grade material parameters, and therefore designs and processes incorporating MHD third grade fluid flow systems are far more likely to give optimum and efficient performance.

Computational analysis of nanofluid and hybrid nanofluid in Darcy’s squeezing flow with entropy optimization

2019 ◽  
Vol 29 (9) ◽  
pp. 3394-3416 ◽  
Author(s):  
Muhammad Ijaz Khan ◽  
Ahmed Alsaedi ◽  
Salman Ahmad ◽  
Tasawar Hayat
Keyword(s):  
Skin Friction ◽  
Entropy Generation ◽  
Variable Temperature ◽  
Entropy Generation Rate ◽  
Squeezing Flow ◽  
Hybrid Nanofluid ◽  
Bejan Number ◽  
Porous Space ◽  
Suction Parameter ◽  
Content Type

Purpose This paper aims to examine squeezing flow of hybrid nanofluid inside the two parallel rotating sheets. The upper sheet squeezes downward, whereas the lower sheet stretches. Darcy’s relation describes porous space. Hybrid nanofluid consists of copper (Cu) and titanium oxide (TiO2) nanoparticles and water (H2O). Viscous dissipation and thermal radiation in modeling are entertained. Entropy generation analysis is examined. Design/methodology/approach Transformation procedure is implemented for conversion of partial differential systems into an ordinary one. The shooting scheme computes numerical solution. Findings Velocity, temperature, Bejan number, entropy generation rate, skin friction and Nusselt number are discussed. Key results are mentioned. Velocity field increases vs higher estimations of squeezing parameter, while it declines via larger porosity variable. Temperature of liquid particles enhances vs larger Eckert number. It is also examined that temperature field dominates for TiO2-H2O, Cu-H2O and Cu-TiO2-H2O. Magnitude of heat transfer rate and skin friction coefficient increase against higher squeezing parameter, radiative parameter, porosity variable and suction parameter. Originality/value The originality of this paper is investigation of three-dimensional time-dependent squeezing flow of hybrid nanomaterial between two parallel sheets. To the best of the authors’ knowledge, no such consideration has been carried out in the literature.

Sign in / Sign up

Export Citation Format

Share Document