Comment on the paper “Heat transfer enhancement in hydromagnetic dissipative flow past a moving wedge suspended by H2O-aluminum alloy nanoparticles in the presence of thermal radiation,Umar Khan,Adnan, Naveed Ahmed,Syed Tauseef Mohyud-Din” [Int J Hydrogen Energy 42 (2017) 24634–24644]

The present comment concerns some doubtful results included in the above paper.     

Response to Comment on the paper “Heat transfer enhancement in hydromagnetic dissipative flow past a moving wedge suspended by H2O-aluminum alloy nanoparticles in the presence of thermal radiation,Umar Khan,Adnan, Naveed Ahmed,Syed Tauseef,Mohyud-Din” [Int J Hydrogen Energy 42 (2017) 24634–24644]

This is reply to the comment on the paper [1].     

Convection heat and mass transfer in a hydromagnetic flow of a second grade fluid in the presence of thermal radiation and thermal diffusion

The convection heat and mass transfer in a hydromagnetic flow of a second grade fluid past a semi-infinite stretching sheet in the presence of thermal radiation and thermal diffusion are considered. The governing coupled non-linear partial differential equations describing the flow problem are transformed into non-linear ordinary differential equations by method of similarity transformation. The resulting similarity equations are solved numerically using Runge-Kutta shooting method. The results are presented as velocity, temperature and concentration fields for different values of parameters entering into the problem. The skin friction, rate of heat transfer and mass transfer are presented numerically in tabular form. In addition, the results obtained showed that these parameters have significant influence on the flow, heat and mass transfer.     

Effect of helical baffles and water-based Al2O3, CuO,and SiO2 nanoparticles in the enhancement of thermal performance for shell and tube heat exchanger

In this study, Shell and tube heat exchanger (STHX) with 22% cut segmental baffles and helical baffles with 20°, 30°, 40° inclination angles are considered for three-dimensional CFD analysis using the ANSYS FLUENT tool to investigate the performance of STHX. OHTC and comprehensive performance index are higher for 40° helical baffles when compared to segmental baffle and 20°, 30° helical baffle heat exchangers with water as working fluid. Hence, further investigations are carried out for 40° helical baffle heat exchangers. Numerical investigations are extended with nanofluids (Al₂O₃, CuO, and SiO₂) at 1%, 3%, and 5% volume concentrations for each nanofluid. Under the same mass flow rates, 40° helical baffles with Al₂O₃ nanofluid as working fluid provided better heat transfer rates when compared to the other two nanofluids and base fluid. Also, the authors noticed that the 5% volume (vol) concentration nanofluids provided better heat transfer enhancements when compared to 1%, 3% volume concentrations, and base fluid. Enhancements (10.33%–8.24%) from lower to the higher mass flow rate in 40° HB with Al₂O₃ nanofluid at 5% volume concentration are observed when compared to water as base fluid.     

Quadratic mixed convective nanofluid flow past a moving yawed cylinder in the presence of thermal radiation and diffusive liquids

The fluid flow around a yawed cylinder helps to understand the practical implications for undersea applications, such as managing transference, separating the boundary layer above submerged blocks, and suppressing recirculating bubbles. As many authors such as Roy, Chiu and Lienhard, Roy and Saikrishnan, and Revathi et al. have analyzed a boundary layer flow over a yawed cylinder, and their work sticks to only forced convection, we are interested to work on mixed convection flow. Therefore, the work of these researchers has stimulated us to work on the present article. As a result, we have examined the work on triple diffusion quadratic mixed convective nanofluid flow over a moving yawed cylinder. The impact of yaw angle, which exists due to the inclination of a vertically moving cylinder away from the origin, is mathematically investigated in the present paper by converting the governing equations into a compatible form using appropriate nonsimilar transformations and the quasilinearization technique. Nanofluids have crucial usages in science and technology, marine engineering, and applications in industries such as plastic, polymer industries, cancer home therapy, and building sciences. Many processes in new engineering areas occur at high temperatures, and knowledge of radiation heat transfer becomes very important for designing the pertinent equipment. Nuclear power plants, gas turbines, and the various propulsion devices for aircraft, missiles, satellites, and space vehicles are examples of such engineering areas. The finite difference approximation is employed to solve the resulting equations. Enhancing the magnitude of thermal radiation enhances the temperature of the liquid and the energy transport strength. However, liquid hydrogen and liquid oxygen species concentration patterns are reduced in nanofluid compared to traditional liquids. At the same time, the outcomes behave conversely in the case of their wall gradients. Furthermore, the temperature of the liquid enhances the enhancing values of Brownian motion and thermophoresis characteristics. Moreover, nanoparticle mass transport augments with enhancing yaw angle and Lewis number values. Both species' concentration profiles decrease for increasing values of yaw angle. The velocity profiles increase for increasing values of velocity ratio parameter in the spanwise and chordwise directions.     

MHD free convective dissipative flow past a porous plate in a porous medium in the presence of radiation and thermal diffusion effects

The problem of a hydromagnetic convective flow of an electrically incompressible viscous conducting fluid past a uniformly moving vertical porous plate is investigated analytically, taking into consideration radiation and thermal diffusion effects. A constant suction velocity is applied to the plate. A uniformly strong magnetic field is supposed to be applied normally to the plate and directed into the fluid region. To find a solution to the problem, an asymptotic series expansion method is used. The effects of thermal diffusion, magnetic field, porosity parameter, thermal radiation, and Grashof number are mainly focused on the discussion of the current problem. Increasing Soret number (Sr) hikes the velocity profile and skin friction but declines Sherwood number. Also, it has been found that, when the magnetic parameter (M) increased, the fluid velocity and the concentration profile decreased. The current results show a good deal of agreement with previously published work. The findings of this study could be relevant in a variety of applications, including diffusion processes involving molecular diffusion of species with molar concentration.     

Heat transfer and buoyancy‐driven convective MHD flow of nanofluids impinging over a thin needle moving in a parallel stream influenced by Prandtl number

The current study focuses on investigating the influence of transverse magnetic field, variable viscosity, buoyancy, variable Prandtl number, viscous dissipation, Joulian dissipation, and heat generation on the flow of nanofluids over thin needle moving in parallel stream. The theory of nanofluids that includes the Buongiorno model featured by slip mechanism, such as Brownian motion and thermophoresis, has been implemented. Further, convective boundary condition and zero mass flux condition are considered. The nondimensionally developed boundary layer equations have been solved by Runge–Kutta–Fehlberg method with shooting technique for different values of parameters. The most relevant outcomes of the present study are that the augmented magnetic field strength, viscosity parameter, buoyancy ratio parameter, and the size of the needle undermine the flow velocity, establishing thicker velocity boundary layer while Richardson number and Brownian motion show opposite trend. Another most important outcome is that increase in the size of the needle, viscous dissipation, convective heating, and heat generation upsurges the fluid temperature, leading to improvement in thermal boundary layer. The effects of different natural parameters on wall shear stress and heat and mass transfer rates have been discussed.     

Numerical Study of Heat and Mass Transfer MHD Viscous Flow Over a Moving Wedge in the Presence of Viscous Dissipation and Heat Source/Sink with Convective Boundary Condition

In this article, the effects of viscous dissipation and internal heat generation/absorption on combined heat and mass transfer MHD viscous fluid flow over a moving wedge in the presence of mass suction/injection with the convective boundary condition are carried out numerically for the various values of dimensionless parameters. With the help of similarity transformation, the momentum, energy, and concentration equations are reduced to a set of dimensionless non‐linear ordinary differential equations. The significance of the dimensionless velocity, temperature, mass profiles, and their gradients are presented in graphical form. Three types of flows—particularly the flat plate, vertical wedge, and stagnation point flows—in favorable and unfavorable regimes are analyzed. The obtained results confirm that the flow field is substantially influenced by the magnetic, stretching/shrinking, pressure, Prandtl number, heat generation/dissipation, and mass suction/injection parameters. Current results indicate that stretching a wall boundary causes an increase in velocity, temperature, shear stress, temperature, and mass gradients while shrinking causes a decreasing trend with these profiles. The special modified form of the current problem is found to be in good agreement with the other published data. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(1): 17–38, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21063     

Effect of radiation absorption and chemical reaction on MHD-free convective flow through a porous medium past an infinite vertical porous plate in the presence of constant heat flux

An incompressible, electrically conducting, and viscous fluid flowing steadily and freely across a uniformly porous media that is partially constrained by an infinitely long vertical porous plate is studied in the present article. Additionally, chemical reaction and radiation absorption effects are seen. Here, a magnetic field of uniform strength is applied transversely to the plate, a normal suction velocity is imposed on the fluid, and the heat flux is considered to be constant. The non-dimensional momentum and energy equations are solved using the method of perturbation. The problem has been analytically resolved, and several parameters, including the Hartmann number, porosity parameter, thermal Grashof number, mass Grashof number, and transport properties like the Sherwood number, skin friction, and plate temperature, are graphically represented. The current study reveals a spike in the radiation absorption effect causes skin friction to drop, but on the other hand, a contrary effect is observed for plate temperature. One of the notable findings of this investigation is that the Sherwood number increases as chemical reaction parameter influence increases.     

Velocity slip,chemical reaction,and suction/injection effects on two-dimensional unsteady MHD mass transfer flow over a stretching surface in the presence of thermal radiation and viscous dissipation

The purpose of this study is to analyze the impact of velocity slip, chemical reaction, and suction/injection on two-dimensional mass transfer effects on unsteady MHD flow over a stretching surface in the presence of thermal radiation and viscous dissipation. The governing time-dependent nonlinear partial differential equations are transformed into nonlinear ordinary differential equations by using similarity transformations. The converted equations are solved using the numerical technique with the help of Keller-Box method. The effect of nondimensional variables is studied and graphically illustrated on velocity, temperature, concentration, friction factor, Nusselt number, and Sherwood number. Concentration and temperature profiles are enhanced and the contrasting pattern for velocity profiles as increasing the velocity slip and magnetic parameter. The concentration profile is diminished as the Schmidt number (Sc) and chemical reaction (C_r) increase. The concentration, velocity, and temperature profiles display a reversal pattern, as the suction and unsteady parameter (A) increase. The findings of this study are very well-acknowledged with current research.     

Terrific effect of H2 on 3D free convection MHD flow of C2H6O2H2O hybrid base fluid to dissolve Cu nanoparticles in a porous space considering the thermal radiation and nanoparticle shapes effects

In this article, the physical aspects of natural convection magnetohydrodynamic flow of Cu/Ethylene glycol-water nanofluid past a porosity vertical stretching sheet under impact of thermal radiation, shape and slip factor and suction/injection process has been analyzed using Runge- Kutta Fehlberg fifth order (RKF 5) numerical method. The influence of variable, different parameters such as nanoparticles shape factor, named hexahedron and Lamina on temperature and velocity profiles are exemplified quantitatively through graphs. Outputs demonstrate thermal radiation impact causes to produce heat and increase the temperature profile by increasing nanofluid molecules energy. Lamina shape nanoparticle has a greater effect on increasing Nusselt number (Nu) compared to hexahedron.