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Special Issue "Numerical Simulation of Convective-Radiative Heat Transfer"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "E: Thermal Management".

Deadline for manuscript submissions: closed (25 May 2020).

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A printed edition of this Special Issue is available here.

Special Issue Editor

Special Issue Information

Dear colleagues,

Heat transfer is the main transport process for various engineering and natural systems. At the same time, the development of modern engineering apparatus and natural bio- and geo-systems is related to a deep understanding of the processes that have progressed in these systems. Convective and radiative heat transfer mechanisms are the dominant modes in the considered systems. Therefore, an in-depth study of these regimes is very important and useful for both the growth of industry and the preservation of natural resources. There are three main methods for an investigation of the considered heat transfer mechanisms. They are theoretical methods, experimental methods, and computational approaches. Theoretical methods are related, generally, to an analytical description of thermal processes using the laws of conservation of mass, momentum, angular momentum, and energy, while experimental analysis deals with an investigation of heat transfer processes using experimental techniques and measurements. The development of computer engineering allows one to use the plentiful opportunities of numerical simulation to obtain a description and an understanding of heat transfer processes. Such an approach includes the advantages of theoretical methods in which analysis can be performed in a wide range of all governing parameters and the advantages of experimental methods where the deep investigation is possible. Therefore, numerical simulation of convective and radiative heat transfer is a very useful and important topic for different fields of industry and various natural systems.

The present Special Issue will focus on the simulation of convective and radiative heat transfer in engineering systems and natural bio- and geo-systems. It is a very good opportunity to combine original manuscripts on the considered topic to present useful guidelines for future research.

Prof. Dr. Mikhail Sheremet
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • convective heat and mass transfer
  • radiative heat transfer
  • turbulent transport
  • phase change materials
  • porous media
  • nanofluids
  • electronics cooling
  • heat exchangers
  • solar collectors
  • thermal power plants
  • bio- and geo-systems

Published Papers (14 papers)

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Editorial

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Editorial
Numerical Simulation of Convective-Radiative Heat Transfer
Energies 2021, 14(17), 5399; https://0-doi-org.brum.beds.ac.uk/10.3390/en14175399 - 30 Aug 2021
Viewed by 363
Abstract
Heat transfer including heat conduction, thermal convection, and thermal radiation is a major transport process that occurs in various engineering and natural systems such as heat exchangers, solar collectors, nuclear reactors, atmospheric boundary layers, electronical and biomedical systems, and others [...] Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)

Research

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Article
Numerical Simulation of the Flow and Heat Transfer in an Electric Steel Tempering Furnace
Energies 2020, 13(14), 3655; https://0-doi-org.brum.beds.ac.uk/10.3390/en13143655 - 15 Jul 2020
Cited by 7 | Viewed by 997
Abstract
Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering [...] Read more.
Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering furnace, a heat-resistant fan is commonly employed to generate moderate gas circulation to obtain adequate temperature homogeneity and heat transfer. Nevertheless, there is a tradeoff because the overall thermal efficiency is expected to reduce because of the high rotating speed of the fan. Therefore, this study numerically investigates the thermal efficiency changes of an electric tempering furnace due to changes in the rotating speed of the fan and the effects on temperature homogeneity and the heat transfer rate to the load. Heat losses through the walls were calculated from the external temperature measurement of the furnace. Four different speeds were simulated: 720, 990, 1350, and 1800 rpm. Thermal homogeneity was improved at higher rotating speeds; this is because the recirculation zone caused by the fan improved the flow mixing and the heat transfer. However, it was found that the thermal efficiency of the tempering furnace decreased as the rotating speed values increased. Therefore, these characteristics should be modulated to obtain a profit when controlling the rotating speed. For example, although thermal efficiency decreases by 20% when the rotating speed is doubled, the heat transfer rate to load is increased by up to 50%, which can be beneficial in decreasing the process of tempering times. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Triple Solutions of Carreau Thin Film Flow with Thermocapillarity and Injection on an Unsteady Stretching Sheet
Energies 2020, 13(12), 3177; https://0-doi-org.brum.beds.ac.uk/10.3390/en13123177 - 19 Jun 2020
Cited by 6 | Viewed by 686
Abstract
Thin films and coatings which have a high demand in a variety of industries—such as manufacturing, optics, and photonics—need regular improvement to sustain industrial productivity. Thus, the present work examined the problem of the Carreau thin film flow and heat transfer with the [...] Read more.
Thin films and coatings which have a high demand in a variety of industries—such as manufacturing, optics, and photonics—need regular improvement to sustain industrial productivity. Thus, the present work examined the problem of the Carreau thin film flow and heat transfer with the influence of thermocapillarity over an unsteady stretching sheet, numerically. The sheet is permeable, and there is an injection effect at the surface of the stretching sheet. The similarity transformation reduced the partial differential equations into a system of ordinary differential equations which is then solved numerically by the MATLAB boundary value problem solver bvp4c. The more substantial effect of injection was found to be the reduction of the film thickness at the free surface and development of a better rate of convective heat transfer. However, the increment in the thermocapillarity number thickens the film, reduces the drag force, and weakens the rate of heat transfer past the stretching sheet. The triple solutions are identified when the governing parameters vary, but two of the solutions gave negative film thickness. Detecting solutions with the most negative film thickness is essential because it implies the interruption in the laminar flow over the stretching sheet, which then affects the thin film growing process. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Finite-Element Simulation for Thermal Modeling of a Cell in an Adiabatic Calorimeter
Energies 2020, 13(9), 2300; https://0-doi-org.brum.beds.ac.uk/10.3390/en13092300 - 06 May 2020
Cited by 5 | Viewed by 675
Abstract
This research obtains a mathematical formulation to determine the heat transfer in a transient state, in a calorimeter cell, considering an adiabatic system. The development of the cell was established and the mathematical model was transiently solved, which approximated the physical phenomenon under [...] Read more.
This research obtains a mathematical formulation to determine the heat transfer in a transient state, in a calorimeter cell, considering an adiabatic system. The development of the cell was established and the mathematical model was transiently solved, which approximated the physical phenomenon under the cell operation. A numerical method for complex geometries was used to validate performance. The results obtained in the transient heat transfer in a cylinder under boundary and initial conditions were compared using an analytical solution and numerical analysis employing the finite-element method with commercial software. The study from the temperature distribution can afford, selection between a cylindrical and spherical geometry, design criteria that are generated by changing parameters such as dimension, temperature, and working fluids to develop an adiabatic calorimeter to measure the heat capacity in fluids. We show the mathematical solution with its initial and boundary conditions as well as a comparison with a numerical solution for a cylindrical cell with a maximum error from 0.075% in the temperature value, along with a theoretical and numerical analysis for a temperature difference of 1 °C. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Semi-Analytical Model for Heat and Mass Transfer Evaluation of Vapor Bubbling
Energies 2020, 13(5), 1104; https://0-doi-org.brum.beds.ac.uk/10.3390/en13051104 - 02 Mar 2020
Cited by 1 | Viewed by 821
Abstract
Multi-stage refrigeration systems cover a wide range of possibilities and are diffusing more and more. The idea that inspired this work derived from the need to have a tool to model the energy behavior of the intercooler inside a multi-stage refrigeration system. In [...] Read more.
Multi-stage refrigeration systems cover a wide range of possibilities and are diffusing more and more. The idea that inspired this work derived from the need to have a tool to model the energy behavior of the intercooler inside a multi-stage refrigeration system. In this work, a semi-analytical model of a single bubble, injected into the liquid of an intercooler of a multi-stage system, has been developed. The developed model is a set of equations derived from the Fourier equation for heat conduction in defined conditions and includes the effects of sensible and latent heat. The vapor bubble is supposed to be injected in the saturated liquid contained in a tank at a defined depth, at an intermediate pressure. The model has been implemented in Matlab and the results show the influence of the liquid surface tension, the injection depth and the thermal diffusivity of the vapor. The model developed here is a useful low-cost tool for evaluating heat transfer optimization of a separator/intercooler of a multi-stage refrigeration system. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Numerical Study of Heated Tube Arrays in the Laminar Free Convection Heat Transfer
Energies 2020, 13(4), 973; https://0-doi-org.brum.beds.ac.uk/10.3390/en13040973 - 21 Feb 2020
Cited by 3 | Viewed by 826
Abstract
Laminar free convection heat transfer from a heated cylinder and tube arrays is studied numerically to obtain the local and average Nusselt numbers. To verify the numerical simulations, the Nusselt numbers for a single cylinder were compared to other authors for the Rayleigh [...] Read more.
Laminar free convection heat transfer from a heated cylinder and tube arrays is studied numerically to obtain the local and average Nusselt numbers. To verify the numerical simulations, the Nusselt numbers for a single cylinder were compared to other authors for the Rayleigh numbers of 103 and 104. Furthermore, the vertically arranged heated tube arrays 4 × 1 and 4 × 2 with the tube ratio spacing SV/D = 2 were considered, and obtained average Nusselt numbers were compared to the existing correlating equations. A good agreement of the average Nusselt numbers for the single cylinder and the bottom tube of the 4 × 1 tube array is proved. On the other hand, the bottom tubes of the 4 × 2 tube array affect each other, and the Nusselt numbers have a different course compared to the single cylinder. The temperature fields for the tube array 4 × 4 in basic, concave, and convex configurations are studied, and new correlating equations were determined. The simulations were done for the Rayleigh numbers in the range of 1.3 × 104 to 3.7 × 104 with a tube ratio spacing S/D of 2, 2.5, and 3. On the basis of the results, the average Nusselt numbers increase with the Rayleigh numbers and tube spacing increasing. The average Nusselt number and total heat flux density for the convex configuration increase compared to the base one; on the other hand, the average Nusselt number decreases for the concave one. The results are applicable to the tube heaters constructional design in order to heat the ambient air effectively. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Experimental and Numerical Study of the Flow and Heat Transfer in a Bubbly Turbulent Flow in a Pipe with Sudden Expansion
Energies 2019, 12(14), 2735; https://0-doi-org.brum.beds.ac.uk/10.3390/en12142735 - 17 Jul 2019
Cited by 11 | Viewed by 1091
Abstract
The flow patterns and heat transfer of a downstream bubbly flow in a sudden pipe expansion are experimentally and numerically studied. Measurements of the bubble size were performed using shadow photography. Fluid phase velocities were measured using a PIV system. The numerical model [...] Read more.
The flow patterns and heat transfer of a downstream bubbly flow in a sudden pipe expansion are experimentally and numerically studied. Measurements of the bubble size were performed using shadow photography. Fluid phase velocities were measured using a PIV system. The numerical model was employed the Eulerian approach. The set of RANS equations was used for modelling two-phase bubbly flows. The turbulence of the carrier liquid phase was predicted using the Reynolds stress model. The peak of axial and radial fluctuations of the carrier fluid (liquid) velocity in the bubbly flow is observed in the shear layer. The addition of air bubbles resulted in a significant increase in the heat transfer rate (up to 300%). The main enhancement in heat transfer is observed after the point of flow reattachment. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Domestic Hot Water Storage Tank Utilizing Phase Change Materials (PCMs): Numerical Approach
Energies 2019, 12(11), 2170; https://0-doi-org.brum.beds.ac.uk/10.3390/en12112170 - 06 Jun 2019
Cited by 11 | Viewed by 1273
Abstract
Thermal energy storage (TES) is an essential part of a solar thermal/hot water system. It was shown that TES significantly enhances the efficiency and cost effectiveness of solar thermal systems by fulfilling the gap/mismatch between the solar radiation supply during the day and [...] Read more.
Thermal energy storage (TES) is an essential part of a solar thermal/hot water system. It was shown that TES significantly enhances the efficiency and cost effectiveness of solar thermal systems by fulfilling the gap/mismatch between the solar radiation supply during the day and peak demand/load when sun is not available. In the present paper, a three-dimensional numerical model of a water-based thermal storage tank to provide domestic hot water demand is conducted. Phase change material (PCM) was used in the tank as a thermal storage medium and was connected to a photovoltaic thermal collector. The present paper shows the effectiveness of utilizing PCMs in a commercial 30-gallon domestic hot water tank used in buildings. The storage efficiency and the outlet water temperature were predicted to evaluate the storage system performance for different charging flow rates and different numbers of families demands. The results revealed that increases in the hot water supply coming from the solar collector caused increases in the outlet water temperature during the discharge period for one family demand. In such a case, it was observed that the storage efficiency was relatively low. Due to low demand (only one family), the PCMs were not completely crystallized at the end of the discharge period. The results showed that the increases in the family’s demand improve the thermal storage efficiency due to the increases in the portion of the energy that is recovered during the nighttime. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Natural Convection of Non-Newtonian Power-Law Fluid in a Square Cavity with a Heat-Generating Element
Energies 2019, 12(11), 2149; https://0-doi-org.brum.beds.ac.uk/10.3390/en12112149 - 05 Jun 2019
Cited by 17 | Viewed by 1560
Abstract
Development of modern technology in microelectronics and power engineering necessitates the creation of effective cooling systems. This is made possible by the use of the special fins technology within the cavity or special heat transfer liquids in order to intensify the heat removal [...] Read more.
Development of modern technology in microelectronics and power engineering necessitates the creation of effective cooling systems. This is made possible by the use of the special fins technology within the cavity or special heat transfer liquids in order to intensify the heat removal from the heat-generating elements. The present work is devoted to the mathematical modeling of thermogravitational convection of a non-Newtonian fluid in a closed square cavity with a local source of internal volumetric heat generation. The behavior of the fluid is described by the Ostwald-de Waele power law model. The defining Navier–Stokes equations written using the dimensionless stream function, vorticity and temperature are solved using the finite difference method. The effects of the Rayleigh number, power-law index, and thermal conductivity ratio on heat transfer and the flow structure are studied. The obtained results are presented in the form of isolines of the stream function and temperature, as well as the dependences of the average Nusselt number and average temperature on the governing parameters. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
How Big Is an Error in the Analytical Calculation of Annular Fin Efficiency?
Energies 2019, 12(9), 1787; https://0-doi-org.brum.beds.ac.uk/10.3390/en12091787 - 10 May 2019
Cited by 4 | Viewed by 1098
Abstract
An important role in the dimensioning of heat exchange surfaces with an annular fin is the fin efficiency. The fin efficiency is usually calculated using analytical expressions developed in the last century. However, these expressions are derived with certain assumptions and simplifications that [...] Read more.
An important role in the dimensioning of heat exchange surfaces with an annular fin is the fin efficiency. The fin efficiency is usually calculated using analytical expressions developed in the last century. However, these expressions are derived with certain assumptions and simplifications that involve a certain error in the calculation. The purpose of this paper is to determine the size of the error due to the assumptions and simplifications made when performing the analytical expression and to present what has the greatest impact on the amount of error, and give a recommendation on how to reduce that error. In order to determine the error, but also to gain a more detailed insight into the physics of heat exchange processes on the fin surface, computational fluid dynamics was applied to the original definition of fin efficiency. This means that a numerical simulation was performed for the actual fin material and for the ideal fin material with infinite thermal conductivity for the selected fin geometry and Re numbers from 2000 to 18,000. The results show that fin efficiency determined by numerical simulations is greater by up to 12.3% than the efficiency calculated analytically. The greatest impact on the amount of error is the assumption of the same temperature of the fin base surface and the outer tube surface and the assumption of equal heat transfer coefficient on the entire fin surface area. Using a newly recommended expression for the equivalent length of the fin tip, it would be possible to calculate the fin efficiency more precisely and thus the average heat transfer coefficient on the fin surface area, which leads to a more accurate dimensioning of the heat exchanger. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Simulation of Vortex Heat Transfer Enhancement in the Turbulent Water Flow in the Narrow Plane-Parallel Channel with an Inclined Oval-trench Dimple of Fixed Depth and Spot Area
Energies 2019, 12(7), 1296; https://0-doi-org.brum.beds.ac.uk/10.3390/en12071296 - 04 Apr 2019
Cited by 12 | Viewed by 1148
Abstract
This article is devoted to the development of the multiblock technique for numerical simulation of vortex heat transfer enhancement (VHTE) by inclined oval-trench dimples. Special attention is paid both to the analysis of numerical predictions of different-type boundary conditions at the wall: T [...] Read more.
This article is devoted to the development of the multiblock technique for numerical simulation of vortex heat transfer enhancement (VHTE) by inclined oval-trench dimples. Special attention is paid both to the analysis of numerical predictions of different-type boundary conditions at the wall: T = const and q = const and to the comparison of the standard and modified shear stress transport models. The article discusses the mechanism of change in the flow structure and secondary flow augmentation due to an increase in a relative length of an oval-trench dimple (at its fixed spot area, depth and orientation) where a long spiral vortex is formed. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
A Stability Analysis for Magnetohydrodynamics Stagnation Point Flow with Zero Nanoparticles Flux Condition and Anisotropic Slip
Energies 2019, 12(7), 1268; https://0-doi-org.brum.beds.ac.uk/10.3390/en12071268 - 02 Apr 2019
Cited by 32 | Viewed by 1794
Abstract
The numerical study of nanofluid stagnation point flow coupled with heat and mass transfer on a moving sheet with bi-directional slip velocities is emphasized. A magnetic field is considered normal to the moving sheet. Buongiorno’s model is utilized to assimilate the mixed effects [...] Read more.
The numerical study of nanofluid stagnation point flow coupled with heat and mass transfer on a moving sheet with bi-directional slip velocities is emphasized. A magnetic field is considered normal to the moving sheet. Buongiorno’s model is utilized to assimilate the mixed effects of thermophoresis and Brownian motion due to the nanoparticles. Zero nanoparticles’ flux condition at the surface is employed, which indicates that the nanoparticles’ fraction are passively controlled. This condition makes the model more practical for certain engineering applications. The continuity, momentum, energy and concentration equations are transformed into a set of nonlinear ordinary (similarity) differential equations. Using bvp4c code in MATLAB software, the similarity solutions are graphically demonstrated for considerable parameters such as thermophoresis, Brownian motion and slips on the velocity, nanoparticles volume fraction and temperature profiles. The rate of heat transfer is reduced with the intensification of the anisotropic slip (difference of two-directional slip velocities) and the thermophoresis parameter, while the opposite result is obtained for the mass transfer rate. The study also revealed the existence of non-unique solutions on all the profiles, but, surprisingly, dual solutions exist boundlessly for any positive value of the control parameters. A stability analysis is implemented to assert the reliability and acceptability of the first solution as the physical solution. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
The Influence of Surface Radiation on the Passive Cooling of a Heat-Generating Element
Energies 2019, 12(6), 980; https://0-doi-org.brum.beds.ac.uk/10.3390/en12060980 - 13 Mar 2019
Cited by 6 | Viewed by 865
Abstract
Low-power electronic devices are suitably cooled by thermogravitational convection and radiation. The use of modern methods of computational mechanics makes it possible to develop efficient passive cooling systems. The present work deals with the numerical study of radiative-convective heat transfer in enclosure with [...] Read more.
Low-power electronic devices are suitably cooled by thermogravitational convection and radiation. The use of modern methods of computational mechanics makes it possible to develop efficient passive cooling systems. The present work deals with the numerical study of radiative-convective heat transfer in enclosure with a heat-generating source such as an electronic chip. The governing unsteady Reynolds-averaged Navier–Stokes (URANS) equations were solved using the finite difference method. Numerical results for the stream function–vorticity formulation are shown in the form of isotherm and streamline plots and average Nusselt numbers. The influence of the relevant parameters such as the Ostrogradsky number, surface emissivity, and the Rayleigh number on fluid flow characteristics and thermal transmission are investigated in detail. The comparative assessment clearly emphasizes the effect of surface radiation on the overall energy balance and leads to change the mean temperature inside the heat generating element. The results of the present study can be applied to the design of passive cooling systems. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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Article
Mixed Convection Stagnation-Point Flow of a Nanofluid Past a Permeable Stretching/Shrinking Sheet in the Presence of Thermal Radiation and Heat Source/Sink
Energies 2019, 12(5), 788; https://0-doi-org.brum.beds.ac.uk/10.3390/en12050788 - 27 Feb 2019
Cited by 25 | Viewed by 1420
Abstract
In this study we numerically examine the mixed convection stagnation-point flow of a nanofluid over a vertical stretching/shrinking sheet in the presence of suction, thermal radiation and a heat source/sink. Three distinct types of nanoparticles, copper (Cu), alumina (Al2O3) [...] Read more.
In this study we numerically examine the mixed convection stagnation-point flow of a nanofluid over a vertical stretching/shrinking sheet in the presence of suction, thermal radiation and a heat source/sink. Three distinct types of nanoparticles, copper (Cu), alumina (Al2O3) and titania (TiO2), were investigated with water as the base fluid. The governing partial differential equations were converted into ordinary differential equations with the aid of similarity transformations and solved numerically by utilizing the bvp4c programme in MATLAB. Dual (upper and lower branch) solutions were determined within a particular range of the mixed convection parameters in both the opposing and assisting flow regions and a stability analysis was carried out to identify which solutions were stable. Accordingly, solutions were gained for the reduced skin friction coefficients, the reduced local Nusselt number, along with the velocity and temperature profiles for several values of the parameters, which consists of the mixed convection parameter, the solid volume fraction of nanoparticles, the thermal radiation parameter, the heat source/sink parameter, the suction parameter and the stretching/shrinking parameter. Furthermore, the solutions were presented in graphs and discussed in detail. Full article
(This article belongs to the Special Issue Numerical Simulation of Convective-Radiative Heat Transfer)
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