Abstract
The hydromagnetic dissipative, heat-absorbing, chemically reactive and optically thick radiative flow of nanofluid over a stretchable surface together with heat and mass transport phenomena is investigated. The prevailing partial differential equations (PDE) of the mathematical model are changed by incorporating apt similarity variables in the form of nonlinear similarity equations. Further, these similarity equations are solved numerically utilizing the Runge-Kutta Fehlberg technique in conjunction with the shooting method. For the numerical explorations, three kinds of nanofluids are prepared by disseminating very fine nanoparticles of titanium oxide (TiO2), aluminium oxide (Al2O3) and copper (Cu) into water. The significance of numerous regulatory flow parameters on the nanofluid velocity, nanofluid temperature, local Nusselt number, species concentration, wall velocity gradient and mass flow rates are examined through different graphical results. Additionally, a quadratic regression approximation analysis is accomplished to analyze the connection between the heat transport rate and regulatory flow parameters. The numerical results reveal that the temperature of Cu-water based nanofluid temperature gets enhanced owing to improvement in the strength of radiation, viscous dissipation and magnetic effects. Further, regression approximation analysis unveils that a slight change in the velocity slip parameter leads in the optimal perturbation in both the shear stress values and heat transfer rate at the stretchable surface. Finally, the validation of numerical results and the developed algorithm of employed computational technique have been done by making a comparison of computed results with the available results under restricted situations.
Introduction
Nowadays, energy resources play a significant role in the growth of human society. Researchers are constantly betrothed to the discovery of novel energy resources. In pursuance, many theoretical and experimental analyses have been accomplished to boost the heat transport rate of several fluids. Nanofluid is a colloidal suspension of nano-sized polymeric, non-metallic/ metallic powder in a conventional fluid which are used to augment heat transport rate for numerous applications. In the past few years, numerous ideas of nanofluids have been suggested as a course for augmenting heat transport fluids performance. The idea of achieving high thermal conductivity in a fluid by mixing very fine metal nanoparticles of diameter into a base fluid was initially proposed by Choi 1 and termed as nanofluids. The fluid characteristics of base fluids such as thermal conductivity and heat transport rate etc. can be influenced by disseminating extremely fine metal/metal oxides particles into fluid. 2 Owing to the novel features, nanofluids are widely used in the nano-medical industry, automobiles, metallurgy, microsystem's cooling, energy conversion, optical and sensor devices.3,4 Rashidi et al. 5 reviewed numerically and experimentally both to identify the significance of nanofluids on condensing and evaporating systems’ performance and also, they discussed the disadvantages of using nanofluid in condensing as well as evaporating systems. Subsequently, the impact of nanoparticles on the efficiency of the system of solar desalination incorporating passive as well as active solar distillation systems was made by Rashidi et al. 6 Ellahi et al. 7 surveyed the heat transfer significance of water-Al2O3 nanofluid stagnation point flow via a permeable wedge. Further, Ellahi et al. 8 extended their investigation to analyse the particle shape impact on the Marangoni convective nanofluid flow. Sharma et al. 9 scrutinized the worth of Soret and Dufour impacts on the flow of natural convective nanofluid via a stretched sheet assuming the inclined magnetic field. Moreover, Sheikholeslami et al. 10 observed that the convection mode of nanofluid is strongly affected by the nanoparticle's shapes. Ma et al. 11 examined that by enhancing the width of the baffle the average values of Nusselt numbers can be improved. Moreover, Nia et al. 12 noticed that only appropriate baffle arrangements can augment the natural convection in case of high Rayleigh values. Izadi et al. 13 investigated the melting rate of hydromagnetic ferro phase variation in a cavity due to the location effect of magnetic sources. Hajjar et al. 14 examined the suspension of free convective nano-encapsulated phase alteration materials in the cavity considering a heated wall. Alsabery et al. 15 performed the irreversibility examination of the free convective flow of nanofluids via a wavy cavity.
The heat absorption/generation are noteworthy to achieve the optimal heat transport performance in various physical phenomena and industries such as in post-accident heat exclusion, Earth's mantle convection process, combustion and fire modelling, metal waste development from spent nuclear fuel, thermal power generation, automobiles, etc. Following this, Eldahab and Aziz 16 inspected the mixed convective, hydromagnetic, steady laminar flow through a uninterruptedly stretchable surface considering the effect of internal heat absorption/generation. Further, Elsayed et al. 17 illustrated features the dynamics of heat-absorbing and varying heat flux fluid with heat transfer via a time-dependent stretchable surface and observed that the rise in the heat sink/source parameter results in the significant rise of stretchable surface temperature and consequently reduce the rate of heat transport of the fluid. The analytical solution was obtained by Hussain et al. 18 to scrutinize the impact of heat absorption on the dynamics of convective flow through a vertical accelerated and rotating moving surface under the inspirations of chemical reaction and Hall effects. Their findings reveal that both the solutal and thermal buoyancy forces have an accelerating impact on the fluid velocities in both the secondary and primary directions of the flow, whereas the chemical reaction and heat absorption have a reversal impact on the flow field. In countless industrial phenomena such as in nuclear plants, electrical power generation, manufacturing of energy conversion system equipment, designing of steadfast apparatus, missiles, satellites, gas turbines, etc. the properties of thermal radiation are important for the surface heat transfer. Owing to the novel significance of thermal radiation, numerous investigators have inspected the consequence of solar radiation upshot on the boundary layered flow, considering various geometries. Uddin et al. 19 dissected the impact of radiation on the heat transport appearances of the Cu-water conveying nanofluid through a shirking porous surface and found that the rate of heat transference is significantly raised, and the width of boundary layer is diminished with the improvement of thermal effects. Govone et al. 20 highlighted the importance of radiation consequence on the micro-reactors thermochemical simulations and concluded that thermal radiation can lead to the evolution of porous solid phases and bifurcation in the nano-liquid. Recently, Qasem et al. 21 investigated the radiation impact on the natural convective nano-liquid in a heated cavity wherein the lower and upper dividers are considered as thermally protected. They found that the temperature dispersal profiles of the nano-liquid are increased with an upsurge in the thermal radiation parameter. Few prominent research articles emphasizing the importance of thermal radiation are reported by Hussain et al.,22–24 Hashim et al., 25 Waqas et al., 26 Thriveni et al., 27 Hussain and Jamshed 28 and Khan et al. 29
In all the above-reported research work, researchers have overlooked the impact of viscous dissipation. Although the influence of viscous dissipation is considered to be weak, but its significance in instrumentations, polymer industry, processing of food items, lubrication, etc., is important as it increases the features of temperature dispersal and consequently enhances the heat transfer rate. Some published research papers exploring the consequence of viscous dissipation on different flow problems are documented by Vajravelu and Hadjinicolaou, 30 Partha et al., 31 Aziz 32 and Shamshuddin et al. 33 Furthermore, Joule dissipation signifies the volumetric heat source features in the flows of hydromagnetic fluids and the unified impact of viscous and Joule dissipations are significant in different heat-treated materials. Owing to this significance, plentiful investigations were carried by the researchers, namely, Seth et al., 34 Daniel 35 and Seth and Singh 36 considering unified effects of Joule and viscous dissipations on the flow field. The unified upshots of Joule and viscous dissipation on the boundary layer, two-dimensional, radiative, steady, incompressible, heat-absorbing and electrically conducted fluid flow over a stretchable surface considering thermal and velocity slip conditions into account are reviewed by Seth et al. 37 The flow features of hydromagnetic Carreau-nanofluid with Joule heating, thermal radiation and viscous dissipation over a stretchy surface was explored by Atif et al. 38 Shah et al. 39 scrutinized the effects of Hall current, Joule and viscous dissipation on the electrically conducted squeezing nanofluid flow within the rotating parallel plates considering the model of Cattaneo-Christov heat flux. Recently, Tassaddiq 40 examined the thermal efficiency of hydromagnetic Cattaneo-Christov hybrid micropolar nanofluid flow under the inspirations of Joule and viscous dissipations. In polymer production, biochemicals, chemical treatment of materials, production of insulated cables, catalysis and combustion mechanism chemical reaction occurs naturally. Owing to this reason, Yasin et al. 41 evaluated the chemical reaction bearing on the heat transference features of two-dimensional, hydromagnetic, heat-absorbing and steady flow induced by a permeable shrinking/stretching surface under the stimulus of thermal radiation. Further, Hashmi et al. 42 considered the noble characteristics of chemical reaction, Joule heating, and viscous dissipation dissipations on dynamics of Oldroyd-B fluid permeated by exothermally and isothermally stretchable disks.
Inspired by the investigations reported above, in this paper, we intended to examine the thermal radiation and heat absorption influences on the hydromagnetic nanofluid flow over a permeable stretching surface. Physical insight of chemical reaction, Joule and viscous dissipations on the flow is captured by disseminating the nanoparticles of copper into water. The temperature and velocity dispersal profiles are compared by considering three kinds of water-nanofluids, namely, water-Cu, water-TiO2 and water-Al2O3 nanofluids. As per our knowledge as well as the present scenario of modern technology, no one has investigated this problem, which may be useful in various metallurgical processes and polymer technology that involves cooling of the uninterrupted strips.
Problem formulation
In this research investigation, the dynamics of steady-state, electrically conducted, radiative, two-dimensional, hydromagnetic and incompressible nanofluid over a stretchy surface is scrutinized. The effects of chemical reaction, heat absorption, Joule and viscous dissipations are also scrutinized on the flow field. The nanofluids are prepared by disseminating very fine spherical particles (radius less than 50 nanometers) of titanium oxide (TiO2), copper (Cu) and aluminium oxide (Al2O3) into the water (H2O). The thermo-physical properties of spherical particles of TiO2, Cu, Al2O3 and H2O are given in Table 1.
The thermo-physical properties of spherical nanoparticles of TiO2, Cu, Al2O3. 43
For modelling of this problem, the Cartesian coordinate system is selected where the stretching surface is associated with the

The schematic depiction of problem.
The below-mentioned assumptions have been made to carry out the present investigation:
The uniform velocity The permeable stretching surface mass flux velocity is assumed as At the stretchable surface, the species concentration and nanofluid temperature are constant and are denoted by An unvarying magnetic field The nanoparticles of TiO2, Cu and Al2O3 and water are in the equilibrium state and also no-slip exists between them. The effects of thermal radiation, heat absorption, Joule and viscous dissipations are considered to improve the heat transfer rate of nanofluid. Because of the non-appearance of a peripheral imposed magnetic field, the significance of polarization is overlooked.
44
Small values of magnetic Reynolds number are chosen to curtail the upshot of the induced magnetic field. Between diffusive species and the nanofluid there exist a linear homogeneous chemical reaction one with a fixed rate
According to the above highlighted assumptions, the governing constitutive equations for the nanofluid velocity, temperature and species concentration are represented as (Yasin et al.,
41
Pal,
45
Rashidi et al.
46
and Hussain et al.
47
):
The expressions of
It is worthy to remark here that all the defined expressions reported in equation (6) are valid for spherical nanoparticles and are not applicable for other shape nanoparticles.
43
Further, the
The equations (2), (10) and (4) are changed to three ordinary differential equations using the equations (11) and (13) and are represented as:
The resulting allied conditions are:
where,
Wall velocity gradient, local nusselt number and mass flow rate
From engineering and practical applications viewpoint, the skin friction coefficient
The expressions of
Numerical solution
The analytical solutions of governing equations (14)-(16) with the accompanying conditions (17) are not possible owing to the high nonlinearity and intricacy. Therefore, the numerical solution of these equations satisfying the accompanying conditions asymptotically are obtained by utilizing the Runge-Kutta-Fehlberg technique (RKF45) in conjunction with the shooting method (Gerald and Wheatley
50
and Kundu and Sarkar.
51
) Further, the Runge-Kutta-Fehlberg technique is accomplished to solve these resulting differential equations wherein the values of
Shooting method
This method is implemented to solve a boundary value problem (BVP) by converting it to the form of an initial value problem. To execute this technique, foremost, from the dimensionless equations (14)-(16), five extremely coupled, nonlinear and first-order differential equations are derived. Further, the random value (guess) at one end of the initial value problem (IVP) is chosen and at the other end, we try to obtain a solution by implementing RKF45 technique by considering appropriate step length l. If we get the convergent solution then we assume that our guess is accurate and correct otherwise we use the Secant method to re-guess. This process is repeated until to get the desired convergent and accurate solution at the other end.
RKF45 technique (Runge-Kutta-Fehlberg technique)
The reliable and convergent solution of an initial value problem can be obtained by solving the problem two times by considering the step lengths l and
At each step, the following six values are being used:
One can found the above-mentioned formula (24) in any advanced text book of numerical analysis. It is significant to mention here that the consideration of fixed step length is not the best strategy even though we get the better convergent solution
Results, discussion and validation
Owing to the intricacy and highly nonlinear nature, the numerical solutions of governing similarity equations (14)-(16) composed with the accompanying conditions (17) are obtained executing the Runge-Kutta-Fehlberg technique in conjunction with the shooting method. The significance of prompting flow parameters on the nanofluid velocity
The distribution profiles of velocity and temperature are compared for three water-driven nanofluids, prepared by mixing very fine spherical particles of TiO2, Al2O3 and Cu into the water through the depicted Figures 2 and 3. This comparison of profiles reveals that TiO2-water nanofluid has higher temperature dispersal and velocity profiles followed by Al2O3-water nanofluid while Cu-water nanofluid has the lowest temperature circulation and velocity profiles. Further, for the particular values of controlling flow parameters, these distribution profiles are nearly overlapped with each other and approach to free stream value.

Comparison of

Comparison of
The effects of volume fraction of nanoparticles

Dispersal profiles of

Distribution profiles of

Dispersal profiles of

Distribution profiles of
It is enumerated from the supplementary
Quadratic regression approximations
In this section, a study of quadratic regression approximation has been accomplished on the numerical findings of the wall temperature gradient and the shear stress function to understand how the properties of dimensionless flow parameters change owing to the slight variation of other flow parameters. During the regression approximation analysis, the remaining flow parameters are considered to be fixed. The approximated numerical entities of
The approximated values of the coefficients have been obtained from the quadratic regression approximation analysis corresponding to the estimated
Conclusions
In this research study, the influence of heat absorption and thermal radiation on the hydromagnetic nanofluid flow via a permeable stretching surface has been examined. Physical insight of chemical reaction, Joule and viscous dissipations on the flow is captured by disseminating the spherical nanoparticles of copper into the water. The important findings of the explorations are summarized below:
The TiO2-water nanofluid temperature and velocity profiles are higher as compared to Al2O3 and Cu-water nanofluids. The nanofluid velocity are strongly retarded owing to augmentation in volume fractions of Cu-nanoparticle, velocity slip factor and magnetic effects while these parameters have reversal impacts on the temperature dispersal profiles. The Cu-water fluid temperature and velocity are upsurged due to the injection while suction parameter has adverse impact. The viscous dissipation is accountable to improve the temperature of Cu-water nanofluid. The wall velocity gradient is reduced due to the enhancement in the values of suction parameter and velocity slip parameter whereas it gets heightened owing to the injection parameter. The heat transport rate over the surface of stretching sheet can be increase by improving the effects of thermal radiation, thermal slip factor and viscous dissipation. The shear stress and the heat transference rate of TiO2-water nanofluid are maximum at the stretching surface followed by Cu-water and Al2O3-water nanofluids. The chemical reaction declines the mass transport rate of Cu-water nanofluid whereas mass diffusion has an opposite influence. A minor change in the velocity slip parameter reasons a maximum perturbation in both the wall velocity gradient and heat transfer rate in contrast to the magnetic effect. The optimal relative error of approximated skin friction coefficients is nearly zero and the convergent rate to this accuracy is more as compared to quadratic regression approximated values of the wall temperature gradient.
Supplemental Material
sj-docx-1-pie-10.1177_09544089221096103 - Supplemental material for Dynamics of heat absorbing and radiative hydromagnetic nanofluids through a stretching surface with chemical reaction and viscous dissipation
Supplemental material, sj-docx-1-pie-10.1177_09544089221096103 for Dynamics of heat absorbing and radiative hydromagnetic nanofluids through a stretching surface with chemical reaction and viscous dissipation by Syed M. Hussain, M. R. Mishra, G. S. Seth and Ali J. Chamkha in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering
Footnotes
Acknowledgement
Authors are obliged to the Deanship of Scientific Research, Islamic University of Madinah, Ministry of Education, KSA for providing the support to execute their research work via research project grant: Tamayuzz Program/2/490.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
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References
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