Mohammad Dehghan Afifi, Bahram Jalili, Amirmohammad Mirzaei, Payam Jalili and Davood Ganji
This study aims to analyze the two-dimensional ferrofluid flow in porous media. The effects of changes in parameters such as permeability parameter, buoyancy parameter, Reynolds…
Abstract
Purpose
This study aims to analyze the two-dimensional ferrofluid flow in porous media. The effects of changes in parameters such as permeability parameter, buoyancy parameter, Reynolds and Prandtl numbers, radiation parameter, velocity slip parameter, energy dissipation parameter and viscosity parameter on the velocity and temperature profile are displayed numerically and graphically.
Design/methodology/approach
By using simplification, nonlinear differential equations are converted into ordinary nonlinear equations. Modeling is done in the Cartesian coordinate system. The finite element method (FEM) and the Akbari-Ganji method (AGM) are used to solve the present problem. The finite element model determines each parameter’s effect on the fluid’s velocity and temperature.
Findings
The results show that if the viscosity parameter increases, the temperature of the fluid increases, but the velocity of the fluid decreases. As can be seen in the figures, by increasing the permeability parameter, a reduction in velocity and an enhancement in fluid temperature are observed. When the Reynolds number increases, an increase in fluid velocity and temperature is observed. If the speed slip parameter increases, the speed decreases, and as the energy dissipation parameter increases, the temperature also increases.
Originality/value
When considering factors like thermal conductivity and variable viscosity in this context, they can significantly impact velocity slippage conditions. The primary objective of the present study is to assess the influence of thermal conductivity parameters and variable viscosity within a porous medium on ferrofluid behavior. This particular flow configuration is chosen due to the essential role of ferrofluids and their extensive use in engineering, industry and medicine.
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Ali Ahmadi Azar, Payam Jalili, Bahram Jalili and D.D. Ganji
This study examines fluid flow within a rectangular porous medium bounded by walls capable of expansion or contraction. It focuses on a non-Newtonian fluid with Casson…
Abstract
Purpose
This study examines fluid flow within a rectangular porous medium bounded by walls capable of expansion or contraction. It focuses on a non-Newtonian fluid with Casson characteristics, incompressibility, and electrical conductivity, demonstrating temperature-dependent impacts on viscosity.
Design/methodology/approach
The flow is two-dimensional, unsteady, and laminar, influenced by a small electromagnetic force and electrical conductivity. The Hybrid Analytical and Numerical Method (HAN method) resolves the constitutive differential equations.
Findings
The fluid’s velocity is influenced by the Casson parameter, viscosity variation parameter, and resistive force, while the fluid’s temperature is affected by the radiation parameter, Prandtl number, and power-law index. Increasing the Casson parameter from 0.1 to 50 results in a 4.699% increase in maximum fluid velocity and a 0.123% increase in average velocity. Viscosity variation from 0 to 15 decreases average velocity by 1.42%. Wall expansion (a from −4 to 4) increases maximum velocity by 19.07% and average velocity by 1.09%. The average fluid temperature increases by 100.92% with wall expansion and decreases by 51.47% with a Prandtl number change from 0 to 7.
Originality/value
Understanding fluid dynamics in various environments is crucial for engineering and natural systems. This research emphasizes the critical role of wall movements in fluid dynamics and offers valuable insights for designing systems requiring fluid flow and heat transfer. The study presents new findings on heat transfer and fluid flow in a rectangular channel with two parallel, porous walls capable of expansion and contraction, which have not been previously reported.
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Tunahan Gunay, Duygu Erdem and Ahmet Ziyaettin Sahin
High surface area-to-volume ratios make nanoparticles ideal for cancer heat therapy and targeted medication delivery. Moreover, ternary nanofluids (TNFs) may possess superior…
Abstract
Purpose
High surface area-to-volume ratios make nanoparticles ideal for cancer heat therapy and targeted medication delivery. Moreover, ternary nanofluids (TNFs) may possess superior thermophysical properties compared to mono- and hybrid nanofluids due to their synergistic effects. In light of this information, the objective of this article is to examine the blood-based TNF flow within convergent/divergent channels under velocity slip and temperature jump.
Design/methodology/approach
Leading partial differential equations corresponding to the problem are transformed into a system of nonlinear ordinary differential equations by using similarity variables. The bvp4c code that uses the finite difference method is used to obtain a numerical solution.
Findings
The effect of nanoparticles may change depending on the characteristics of flow near the wall. The properties and proportions of the used nanoparticles become important to control the flow. When TNF was used, an increase in the Nusselt number between 4.75% and 6.10% was observed at low Reynolds numbers. At high Reynolds numbers, nanoparticles reduce the Nusselt number and skin friction coefficient values under some special flow conditions. Importantly, the effects of second-order slip on engineering parameters were also investigated. Furthermore, the Nusselt number increases with increasing shape factor.
Research limitations/implications
Obtained results of the study can be beneficial in both nature and engineering, especially blood flow in veins.
Originality/value
The main innovations of this study are the usage of blood-based TNF and the examination of the effect of shape factor in convergent/divergent channels with second-order velocity slip.
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Yufeng Ren, Changqing Bai and Hongyan Zhang
This study aims to investigate the formation and characteristics of Taylor bubbles resulting from short-time gas injection in liquid-conveying pipelines. Understanding these…
Abstract
Purpose
This study aims to investigate the formation and characteristics of Taylor bubbles resulting from short-time gas injection in liquid-conveying pipelines. Understanding these characteristics is crucial for optimizing pipeline efficiency and enhancing production safety.
Design/methodology/approach
The authors conducted short-time gas injection experiments in a vertical rectangular pipe, focusing on Taylor bubble formation time and stable length. Computational fluid dynamics simulations using large eddy simulation and volume of fluid models were used to complement the experiments.
Findings
Results reveal that the stable length of Taylor bubbles is significantly influenced by gas injection velocity and duration. Specifically, high injection velocity and duration lead to increased bubble aggregation and recirculation region capture, extending the stable length. Additionally, a higher injection velocity accelerates reaching the critical local gas volume fraction, thereby reducing formation time. The developed fitting formulas for stable length and formation time show good agreement with experimental data, with average errors of 6.5% and 7.39%, respectively. The predicted values of the formulas in glycerol-water and ethanol solutions are also in good agreement with the simulation results.
Originality/value
This research provides new insights into Taylor bubble dynamics under short-time gas injection, offering predictive formulas for bubble formation time and stable length. These findings are valuable for optimizing industrial pipeline designs and mitigating potential safety issues.
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Lioua Kolsi, A.M. Rashad, Nirmalendu Biswas, M.A. Mansour, Taha Salah, Aboulbaba Eladeb and Taher Armaghani
This paper aims to explore, through a numerical study, buoyant convective phenomena in a porous cavity containing a hybrid nanofluid, taking into account the local thermal…
Abstract
Purpose
This paper aims to explore, through a numerical study, buoyant convective phenomena in a porous cavity containing a hybrid nanofluid, taking into account the local thermal nonequilibrium (LTNE) approach. The cavity contains a solid block in the shape of a cross (+). It will be helpful to develop and optimize the thermal systems with intricate geometries under LTNE conditions for a variety of applications.
Design/methodology/approach
To attain the objective, the system governing partial differential equations (PDEs), expressed as functions of the current function and temperature, and are solved numerically by the finite difference approach. The authors carefully examine the heat transfer rates and dynamics of the micropolar hybrid nanofluid by presenting fluid flow contours, isotherms of the liquid and solid phases, as well as contours of streamlines, isotherms and concentration of the fluid. Key parameters analyzed include heated length (B = 0.1–0.5), porosity (ε = 0.1–0.9), heat absorption/generation (Q = 0–8), length wave (λ = 1–3) and the interphase heat transfer coefficient (H* = 0.05–10). The equations specific to the flow of a micropolar fluid are converted into classical Navier–Stokes equations by increasing the porosity and pore size.
Findings
The results showed that the shape, strength and position of the fluid circulation are dictated by the size of the inner obstacle (B) as well as the effective length of the heating wall. The lower value of obstruction size, as well as heating wall length, leads to a higher rate of heat transfer. Heat transfer is much higher for the higher amount of heat absorption instead of heat generation (Q). The higher porosity values lead to lesser fluid resistance, which leads to a superior heat transfer from the hot source to the cold walls. The surface waviness of 4 leads to superior heat transfer related to any other waviness.
Research limitations/implications
This work can be further investigated by looking at thermal performance in the existence of various-shaped obstructions, curvature effects, orientations, boundary conditions and other variables. Numerical simulations or experimental studies in different multiphysical contexts can be used to achieve this.
Practical implications
Many technical fields, including heat exchanging unit, crystallization processes, microelectronic units, energy storage processes, mixing devices, food processing, air conditioning systems and many more, can benefit from the geometric configurations investigated in this study.
Originality/value
This work numerically explores the behavior of micropolar nanofluids (a mixture of copper, aluminum oxide and water) within a porous inclined enclosure with corrugated walls, containing a solid insert in the shape of a cross in the center, under the oriented magnetic field, by applying the nonlocal thermal equilibrium model. It analyzes in detail the heat transfer rates and dynamics of the micropolar nanoliquid by presenting the flow patterns, the temperature of liquid and solid phases, as well as the variations in the flow, thermal and concentration fields of the fluid.
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Ali Akbar Abbasian Arani and Ali Memarzadeh
Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and…
Abstract
Purpose
Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and improve the heat exchange. This paper aims to present an improved dual-flow parabolic trough collector (PTC). For this purpose, the effect of an absorber roof, a type of turbulator and a grooved absorber tube in the presence of nanofluid is investigated separately and simultaneously.
Design/methodology/approach
The FLUENT was used for solution of governing equation using control volume scheme. The control volume scheme has been used for solving the governing equations using the finite volume method. The standard k–e turbulence model has been chosen.
Findings
Fluid flow and heat transfer features, as friction factor, performance evaluation criteria (PEC) and Nusselt number have been calculated and analyzed. It is showed that absorber roof intensifies the heat transfer ratio in PTCs. Also, the combination of inserting the turbulator, outer corrugated and inner grooved absorber tube surface can enhance the PEC of PTCs considerably.
Originality/value
Results of the current study show that the PTC with two heat transfer fluids, outer and inner surface corrugated absorber tube, inserting the twisted tape and absorber roof have the maximum Nusselt number ratio equal to 5, and PEC higher than 2.5 between all proposed arrangements for investigated Reynolds numbers (from 10,000 to 20,000) and nanoparticles [Boehmite alumina (“λ-AlOOH)”] volume fractions (from 0.005 to 0.03). Maximum Nusselt number and PEC correspond to nanoparticle volume fraction and Reynolds number equal to 0.03 and 20,000, respectively. Besides, it was found that the performance evaluation criteria index values continuously grow by an intensification of nanoparticle volume concentrations.
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Boussouffi Mustapha and Amina Sabeur
This study aims to provide an in-depth analysis of entropy generation (EG) during natural convection within the annular space between confocal elliptic cylinders, with a specific…
Abstract
Purpose
This study aims to provide an in-depth analysis of entropy generation (EG) during natural convection within the annular space between confocal elliptic cylinders, with a specific focus on the influence of Brownian motion on nanofluid behavior.
Design/methodology/approach
A finite volume control method was used to conduct a detailed numerical analysis, examining the behavior of various nanofluids across a range of volume concentrations (2%–6%) and Rayleigh numbers. The study explores heat transfer (HT) and fluid flow mechanisms, particularly highlighting the role of nanoparticle Brownian motion in enhancing thermal conductivity.
Findings
The findings reveal that increased Rayleigh numbers significantly improve HT rates, while at lower Rayleigh values, EG is primarily governed by thermodynamic irreversibility. At higher Rayleigh numbers, this irreversibility plays a less dominant role in overall entropy production.
Originality/value
This study offers a novel perspective on the interplay between Rayleigh numbers, Brownian motion and EG, providing valuable insights for optimizing HT processes in engineering applications involving nanofluids.
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Ashvani Kumar, Anjali Bhardwaj and Dharmendra Tripathi
Surface properties (smooth or roughness) play a critical role in controlling the wettability, surface area and other physical and chemical properties like fluid flow behaviour…
Abstract
Purpose
Surface properties (smooth or roughness) play a critical role in controlling the wettability, surface area and other physical and chemical properties like fluid flow behaviour over the rough and smooth surfaces. It is reported that rough surfaces are offering more significant insights as compared to smooth surfaces. The purpose of this study is to examine the effects of surface roughness in the diverging channel on physiological fluid flows.
Design/methodology/approach
A mathematical formulation based on the conservation of mass and momentum equations is developed to derive exact solutions for the physical quantities under the assumption of low Reynolds numbers and long wavelengths, which are appropriate for biological transport scenarios.
Findings
The results reveal that an increase in surface roughness reduces axial velocity and volumetric flow rate while increasing pressure distribution and turbulence in skin friction.
Research limitations/implications
These findings offer valuable insights for biological flow analysis, highlighting the effects of surface roughness, non-uniformity of the channel and magnetic fields.
Practical implications
These findings are very much applicable for designing the pumping devices for transportation of the fluids in non-uniform channels.
Originality/value
This study examines the impact of surface roughness on the peristaltic pumping of viscoelastic (Jeffrey) fluids in diverging channels with transverse magnetic fields.
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Nirmal K. Manna, Abhinav Saha, Nirmalendu Biswas and Koushik Ghosh
This paper aims to investigate the thermal performance of equivalent square and circular thermal systems and compare the heat transport and irreversibility of magnetohydrodynamic…
Abstract
Purpose
This paper aims to investigate the thermal performance of equivalent square and circular thermal systems and compare the heat transport and irreversibility of magnetohydrodynamic (MHD) nanofluid flow within these systems.
Design/methodology/approach
The research uses a constraint-based approach to analyze the impact of geometric shapes on heat transfer and irreversibility. Two equivalent systems, a square cavity and a circular cavity, are examined, considering identical heating/cooling lengths and fluid flow volume. The analysis includes parameters such as magnetic field strength, nanoparticle concentration and accompanying irreversibility.
Findings
This study reveals that circular geometry outperforms square geometry in terms of heat flow, fluid flow and heat transfer. The equivalent circular thermal system is more efficient, with heat transfer enhancements of approximately 17.7%. The corresponding irreversibility production rate is also higher, which is up to 17.6%. The total irreversibility production increases with Ra and decreases with a rise in Ha. However, the effect of magnetic field orientation (γ) on total EG is minor.
Research limitations/implications
Further research can explore additional geometric shapes, orientations and boundary conditions to expand the understanding of thermal performance in different configurations. Experimental validation can also complement the numerical analysis presented in this study.
Originality/value
This research introduces a constraint-based approach for evaluating heat transport and irreversibility in MHD nanofluid flow within square and circular thermal systems. The comparison of equivalent geometries and the consideration of constraint-based analysis contribute to the originality and value of this work. The findings provide insights for designing optimal thermal systems and advancing MHD nanofluid flow control mechanisms, offering potential for improved efficiency in various applications.
Graphical Abstract
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This study aims to investigate the heat and mass transfer characteristics of a temperature-sensitive ternary nanofluid in a porous medium with magnetic field and the Soret–Dufour…
Abstract
Purpose
This study aims to investigate the heat and mass transfer characteristics of a temperature-sensitive ternary nanofluid in a porous medium with magnetic field and the Soret–Dufour effect through a tapered asymmetric channel. The ternary nanofluid consists of Boron Nitride Nanotubes (BNNT), silver (Ag) and copper (Cu) nanoparticles, with a focus on understanding the thermal behaviour and performance across mono, hybrid and tri-hybrid nanofluids. This paper also examines the thermal behaviour of MHD oscillatory nanofluid flow and carries out an uncertainty analysis of the model using the Taguchi method.
Design/methodology/approach
The governing equations for this system are transformed into coupled linear partial differential equations using non-similarity transformations and solved numerically with the Crank–Nicolson scheme. The impact of temperature sensitivity at three distinct temperatures (5°C, 20°C and 60°C) is incorporated to analyse variations in viscosity and Prandtl number. The study also examines the combined effects of Soret–Dufour numbers and thermal radiation on heat and mass transfer within the nanofluid.
Findings
The results demonstrate that the inclusion of BNNT, Ag and Cu nanoparticles significantly enhances heat and mass transfer rate, with copper nanoparticles showing superior performance in terms of skin friction and heat transfer rates. The Soret and Dufour effects play critical roles in modulating heat and mass diffusion within tri-hybrid nanofluids. The study reveals that temperature sensitivity alters heat and mass transfer characteristics depending on the temperature range, with pronounced variations at elevated temperatures. The influence of thermal radiation and the Peclet number is found to significantly impact temperature distribution and overall heat transfer performance within the asymmetric channel.
Originality/value
To the best of the authors’ knowledge, this study is the first to analyse the heat and mass diffusion in a ternary nanofluid composed of BNNT, Ag and Cu nanoparticles, considering porous media, oscillatory flow and thermal radiation within a tapered asymmetric channel. The research extends to a novel examination of temperature sensitivity in mono, hybrid and tri-hybrid nanofluids at varying temperature gradients. Furthermore, a comparative analysis of skin friction and heat transfer rates between copper, alumina and ferro composites is presented for optimising the nanofluid performance.