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1

Comparative experimental analysis of fluid flow in a concentric tube exchanger having semi hollow cylindrical macro inserts with nanofluid and base fluid

Kaushik Shivasheesh, Singh Mahar Vikas, Singh Satyendra, Kshetri Rahul, Kumar Bhupendra, Singh Mehta Jagdish, Raj Paul Ashwarya, Kumar Satish, Vashisth Samriddhi, Singh Pundir Raj, Kumar Amit

Archives of Thermodynamics

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2024

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Vol. 45, no 2

205--212

EN

Nanofluids represent a novel category of advanced heat transfer fluids composed of nanoparticles within a size range of 1-20 nm dispersed in a base fluid such as water. Contemporary research predominantly focuses on incorporating nanoparticles like Al2O3 and ZnO into the water at a 0.1% volume fraction to create nanofluids. Recent investigations aim to optimize thermal performance by introducing nanoparticles into the base fluids and inducing turbulence through various macro-inserts. Key factors influencing heat exchanger efficiency enhancement include geometric parameters, thermal conductivity and volume fraction. This study endeavours to analyse the thermal and fluid flow characteristics of a proposed nanofluid, augmenting thermal transfer through computational simulations and experimental validation, achieving an error margin of 3%-5%. The impact of rectangular micro inserts, with dimensions of 4 cm in height and longitudinal spacings of 5 cm and 11.5 cm, on the heat transfer rate is examined to enhance fluid flow turbulence. Results indicate that among different geometric profiles, the insert with a spacing of 11.5 cm demonstrates superior performance, yielding higher heat transfer rates and Nusselt numbers. This research holds significant implications for various industries including thermal, power, aviation, space and automotive sectors, particularly in the utilization of concentric tube heat exchangers across diverse applications. By exploring novel geometrical and fluid domains within heat exchangers, this study unveils promising avenues for enhancing the heat transfer efficiency compared to conventional methods, highlighting the potential for further investigation into alternative materials and configurations for heat elimination enhancement.

2

Computer simulation of heat and mass transfer effects on nanofluid flow of blood through an inclined stenosed artery with hall effect

Mishra Nidhish Kumar

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 1

129--138

EN

The present study deals with the analysis of heat and mass transfer for nanofluid flow of blood through an inclined stenosed artery under the influence of the Hall effect. The effects of hematocrit-dependent viscosity, Joule heating, chemical reaction and viscous dissipation are taken into account in the governing equations of the physical model. Non-dimensional differential equations are solved using the finite difference method, by taking into account the no-slip boundary condition. The effects of different thermophysical parameters on the velocity, temperature, concentration, shear stress coefficient and Nusselt and Sherwood numbers of nano-biofluids are exhaustively discussed and analysed through graphs. With an increase in stenosis height, shear stress, the Nusselt number and the Sherwood number are computed, and the impacts of each are examined for different physical parameters. To better understand the numerous phenomena that arise in the artery when nanofluid is present, the data are displayed graphically and physically described. It is observed that as the Hartman number and Hall parameter increase, the velocity drops. This is as a result of the Lorentz force that the applied magnetic field has generated. Blood flow in the arteries is resisted by the Lorentz force. This study advances the knowledge of stenosis and other defects’ non-surgical treatment options and helps reduce post-operative consequences. Moreover, ongoing research holds promise in the biomedical field, specifically in magnetic resonance angiography (MRA), an imaging method for artery examination and anomaly detection.

3

Palani G., Arutchelvi A.

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 1

71--83

EN

An analysis has been carried out to study the two-dimensional free convective boundary layer MHD nanofluid flow past an inclined plate with heat generation, chemical reaction and radiation effects under convective boundary conditions. The partial differential equations describing the flow are coupled nonlinear. They have been reduced to nonlinear ordinary differential equations by utilizing a similarity transformation, which is then solved numerically with the aid of the Runge-Kutta-based shooting technique. Graphs depict the influence of different controlling factors on the velocity, temperature, and concentration profiles. Numerical findings for skin friction, Nusselt number and Sherwood number are reviewed for distinct physical parameter values. In a limited sense, there is a good correlation between the current study's results and those of the earlier published work.

4

Numerical study of heating transfer by natural convection in an inclined elliptical cylinder charged with nanofluid

Amroune Amina, Bouras Abdelkrim, Taloub Djedid, Driss Zied

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 3

28--41

EN

In this paper, thermal transfer with natural convection in a tilted annular cylinder with a Cu-water nanofluid has been numerically studied. The hot interior and cold exterior elliptical surfaces of the enclosure were maintained at constant temperatures Th and Tc , respectively. The governing equations were solved by the stream function-vorticity approach. The finite volume approach was utilized to discretise the controlling equations. The volume fraction range of the nanoparticles and the Rayleigh number was as follows: [...] respectively. The inclination angles were γ=30°,45°,and 60°. Results were given as isotherm contours, streamlines, average and local Nusselt numbers. The results indicate that the thermal transfer ratio increases with an increase in the tilt angle, regardless of the nanoparticle size values. and the impact of the inclination angle on the heating transfer rate is more important the higher the Rayleigh number and the more convection there is.

5

Unsteady hydromagnetic mixed convection of a radiating and reacting nanofluid in a microchannel with variable properties

Kefene Mesfin Zewde, Makinde Oluwole Daniel, Enyadene Lemi Guta

Engineering Transactions

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2023

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Vol. 71, iss. 1

53--79

EN

Unsteady MHD mixed convection of nanofluid heat transfer in a permeable microchannel with temperature-dependent fluid properties is studied under the influence of a first-order chemical reaction and thermal radiation. The viscosity and thermal conductivity are assumed to be related to temperature exponentially. Using suitable dimensionless variables and parameters, the governing partial differential equations (PDEs) are transformed to their corresponding dimensionless forms solved numerically by a semi-discretization finite difference scheme along with the Runge-Kutta-Fehlberg integration technique. The effects of model parameters on the profiles of velocity, temperature, concentration, skin friction, the Nusselt number, and the Sherwood number are discussed qualitatively with the aid of graph.

6

Thermodynamic analysis of radiating nanofluids mixed convection within concentric pipes filled with a porous medium

Makinde Oluwole Daniel, Mabood Fazle, Khan Waqar Ahmed, Makinde Anuoluwa Esther

Engineering Transactions

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2023

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Vol. 71, iss. 3

419--438

EN

In this study, the entropy generation resulting from heat and mass transfer of waterbased nanofluid through an annulus within two concentric vertical pipes filled with a porous medium is investigated. This study considers the effects of thermal radiation, viscous dissipation, thermal buoyancy, and axial pressure gradient in addition to heat and mass transfer. Brownian motion and thermophoresis have been introduced through the Buongiorno model. The similarity solution was used to solve nonlinear ordinary differential equations. The RungeKutta-Fehlberg method is used to solve these equations with the related boundary conditions. The effects of pertinent parameters such as pressure gradient, thermal radiation, viscosity parameter, thermophoretic parameter, Brownian motion parameter, and Eckert number are investigated numerically. This study found that the Bejan number increases as the viscosity parameter increases and decreases as the other active parameters increase. As the radiation parameter, thermophoretic parameter, Brownian parameter, and Eckert number increase, the Nusselt number decreases. The total entropy generation rate is found to increase with the fluid viscosity rate, Grashof number, thermal Biot number, and variable pressure gradient. However, the Bejan number is found to decrease with these parameters, as well as the Prandtl number.

7

Numerical study of MHD Williamson-nano fluid flow past a vertical cone in the presence of suction/injection and convective boundary conditions

Sathyanarayana Manthri, Goud Tamtam Ramakrishna

Archives of Thermodynamics

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2023

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Vol. 44, no 2

115--138

EN

The primary objective is to perform a numerical synthesis of a Williamson fluid that has nanoparticles added to it and is directed toward a vertical cone in a uniform transverse magnetic field, under heat and mass transport, suction and injection, and convective boundary conditions. For this particular fluid flow, by utilising similarity transformations, the partial differential equations are transformed into ordinary differential equations. Calculating these kinds of equations with their suitable bounds requires the Runge–Kutta technique in combining a shooting strategy. The functions of a vast number of parameters are graphically represented and assessed on flow field profiles. The results show the local skin friction, local Nusselt number, and local Sherwood number and the changing values of the flow constraints. Finally, the results are compared to those from the previously published works and found to be in good agreement.

8

Computational analysis of soret and dufour effects on nanofluid flow through a stenosed artery in the presence of temperature-dependent viscosity

Mishra Nidhish K.

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 2

246--263

EN

In this study, the Soret and Dufour effects in a composite stenosed artery were combined with an analysis of the effect of varying viscosity on copper nanofluids in a porous medium. Blood viscosity, which changes with temperature, is taken into account using the Reynolds viscosity model. The finite difference approach is used to quantitatively solve the governing equations. For use in medical applications, the effects of the physical parameters on velocity, temperature and concentration along the radial axis have been investigated and physically interpreted. The results are graphically displayed and physically defined in order to facilitate comprehension of the various phenomena that occur in the artery when nanofluid is present. It is observed that the Soret effect increases the rate of heat transfer but decreases the rate of mass transfer. The new study enhances knowledge of non-surgical treatment options for stenosis and other abnormalities, hence reducing post-operative complications. Additionally, current research may have biomedical applications such as magnetic resonance angiography (MRA), which provide a picture of an artery and enable identification of any anomalies, and thus may be useful

9

Zastosowanie nanocząstek do modyfikacji cieczy elektroizolacyjnych stosowanych w transformatorach energetycznych

Szcześniak Dominik, Przybyłek Piotr

Przegląd Elektrotechniczny

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2022

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R. 98, nr 6

62--65

PL

Jedną z obecnie rozwijanych metod poprawy właściwości cieczy elektroizolacyjnych jest ich modyfikacja przy użyciu nanoproszków. Poprawa parametrów cieczy zależy od rodzaju zastosowanego nanoproszku, wielkości nanocząstek, jak również od sposobu preparacji nanocieczy. Aktualnie na świecie prowadzone są badania ukierunkowane głównie na poprawę wytrzymałości elektrycznej oraz przewodności cieplnej modyfikowanych cieczy bazowych. W artykule przedstawiono przegląd stosowanych nanomodyfikatorów, metody preparacji nanokoloidów oraz omówiono zagadnienia związane z ich stabilnością.

EN

One possibility to improve the parameters of insulating liquids is their modification by means of nanopowders. The improvement of the dielectric fluid parameters depends on the type and size of the nanopowder as well as on the method of nanofluid preparation. Research conducted around the world are mainly focused on improvement the electrical strength and thermal conductivity of modified insulating liquids. The article presents an overview of nanomodifiers, methods of nanocolloids preparation and the issues related to their stability.

10

Heat transfer by natural convection from a heated square inner cylinder to its elliptical outer enclosure utilizing nanofluids

Bouras Abdelkrim, Taloub Djedid, Driss Zied, Debka Siham

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 2

22--34

EN

In this paper a numerical study of natural convection of stationary laminar heat transfers in a horizontal ring between a heated square inner cylinder and a cold elliptical outer cylinder is presented. A Cu-water nanofluid flows through this annular space. Different values of the Rayleigh number and volume fraction of nanoparticles are studied. The system of equations governing the problem was solved numerically by the fluent calculation code based on the finite volume method and on the Boussinesq approximation. The interior and exterior surfaces are kept at constant temperature. The study is carried out for Rayleigh numbers ranging from 310 to 510. We have studied the effects of different Rayleigh numbers and volume fraction of nanoparticles on natural convection. The results are presented as isotherms, isocurrents, and local and mean Nusselt numbers. The aim of this study is to study the influence of the thermal Rayleigh number and volume fraction of nanoparticles on the heat transfer rate.

11

On the onset of thermal instability of a porous medium layer saturating a Jeffrey nanofluid

Rana Gian C., Gautam Poonam Kumari

Engineering Transactions

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2022

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Vol. 70, iss. 2

123--139

EN

The onset of stationary convection in thermal instability of porous layer saturating a Jeffrey nanofluid is studied. The behaviour of nanofluid is described by a Jeffrey fluid model and the porous layer is assumed to follow Darcy’s law. Due to the presence of the Jeffrey parameter and nanoparticles, the momentum-balance equation of fluid is modified. The linear stability analysis and normal modes analysis method are utilised to derive the dispersion relation for the Rayleigh number in terms of various parameters for free-free boundaries. The effects of the Jeffrey parameter, Lewis number, modified diffusivity ratio, nanoparticles’ Rayleigh number and medium porosity on the physical system are discussed analytically and graphically.

12

Natural convection flow in semi-trapezoidal porous enclosure filled with alumina-water nanofluid using Tiwari and das’ nanofluid model

Vedavathi Nallapati, Venkatadri Kothuru, Fazuruddin Syed, Raju G. Sankara Sekhar

Engineering Transactions

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2022

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Vol. 70, iss. 4

303--318

EN

Nowadays, optimal parameters are necessary for heat transfer enhancement in different practical applications. A numerical simulation of natural convection in a semi-trapezoidal enclosure embedded with porous medium is presented. Stream function and temperature using the Darcy–Boussinesq approximation and Tiwari and Das’ nanofluid model with new more realistic empirical correlations for the physical properties of the nanofluids are formulated. The developed partial differential equations are employed with the help of the stream function approach. The in-house developed computational MATLAB code is validated with the previously published work. The impact of a wide range of governing parameters on fluid flow patterns and temperature gradient variations is presented. The thermal Rayleigh number (Ra) can be a control key parameter for heat and convective flow. Thermal dispersion effects are also examined in this study. An increase in the Rayleigh number leads to an increase in heat transfer, where one can find a reduction of convective heat transfer with φ.

13

Convective Heat Transfer in Heat Exchangers Using Nanofluids: A Review

Reddy Goda Sreenivasulu, Kalaivanan Ramasamy, Kumar Rampelli Uday, Krishna Varma K. P. V.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 3

193--201

EN

Enhancing the Convective heat transfer in the carrier fluids, by augmenting the thermal conductivity in fluids, with nano particles is one of the passive techniques. Enhancement in the thermal conductivity in the carrier fluids can be achieved by suspending particles of nano-size into the base fluids, such colloidal suspensions are called as nanofluids. Nanofluids are proven fluids which improve the convective transfer of heat in the base fluids in the heat exchangers. But still, there are lot of challenges that are existing in understanding the mechanisms of enhancement of convective heat transfer for large scale applications. In this work, an attempt is made to summarize recent advancements on augmentation of convective heat transfer in heat exchangers in turbulent flows using various nanofluids and present various setbacks for the development of nanofluids for critical applications.

14

Artificial Neural Network Technique for Estimating the Thermo-Physical Properties of Water-Alumina Nanofluid

Ravi Babu Sajja, Krishna Varma K. P. V., Mohan Kunapuli Siva Satya

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 2

97--106

EN

With its superior thermo-physical characteristics to the carrier fluid, nanofluid is the most impactful heat transfer fluid. Thermal conductivity, density, viscosity, specific heat, coefficient of volumetric expansion, and other thermo-physical parameters play an important part in the thermal management of any heat transfer application. This thermal management governs the service life of an equipment or apparatus, which dissipates heat during its operation. If the equipment is well-managed thermally, then its service life will be extended. Otherwise the equipment stops functioning due to excess heat. Thermo-physical properties of nanofluid vary with the change in the concentration of nanoparticles. Estimation of the properties with the varying concentrations of the nanoparticles is time consuming and is economically not viable. There were many empirical models available in the literature for determining the thermo-physical properties of nanofluids. However, each model provides different values of thermo-physical properties and choosing the best model among the models available is a complex task. In this regard, to avoid the complication in choosing the best model, and in order to envisage the thermo-physical properties of the nanofluid, the Artificial Neural Network (ANN) technique was used. This technique is widely used among the researchers for various applications. The ANN approach was utilized in this work to estimate viscosity and thermal conductivity of water-based Al2O3 nanofluid for volume fractions between 0.01% and 0.1%. For thermal conductivity, mean square error (MSE) was observed as 4.504e-09 and for viscosity, it was observed as 6.4742e-09. Training times were 5 seconds and 4 seconds for thermal conductivity and viscosity datasets, respectively.

15

The natural convection inside a 3D triangular cross section cavity filled with nanofluid and included cylinder with different arrangements

Ghoben Zainab Kareem, Hussein Ahmed Kadhim

Diagnostyka

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2022

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Vol. 23, No. 2

no. art. 2022205

EN

In this paper the laminar unsteady natural convection heat transfer of (Al2O3-water) nanofluid inside 3D triangular cross section cavity was investigated. The cavity was heated differentially, the vertical walls were kept at different constant temperatures. The left hot and the right cold. The effect of the solid volume fraction was examined for two values and compared with the pure water results. The (Ra) range studied was (103≤Ra≤106). Inserting cylindrical body inside the cavity also investigated in three cases. One concentric cylinder has radius (15%) of the cavity side length. The other cases were of two cylinders having radius (7.5%) of the cavity side length, aligned vertically or nonaligned. The results show that the higher solid volume fraction gives the maximum enhancement of the average (Nu) and this enhancement increases with (Ra) increase. For the cases with inner cylinders, the average (Nu) enhanced for the case of double cylinders over single cylinder. On other hand, the nonaligned position of the cylinders giving more enhancement than other position. As like as, the location of maximum horizontal or vertical velocities were varied with the cylinders position while (Ra) has no effect.

16

Numerical study of car radiator using dimple roughness and nanofluid

Thapa Robin Kumar, Bisht Vijay Singh, Bhandari Prabhakar, Rawat Kamal Singh

Archives of Thermodynamics

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2022

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Vol. 43, no 3

125--140

EN

Thermal augmentation in flat tube of car radiator using different nanofluids has been performed more often, but use of artificial roughness has been seldom done. Artificial roughness in the form of dimple is used in the present research work. Present study shows the impact of dimple shaped roughness and nanofluid (Al2O3/pure water) on the performance of car radiator. The pitch of dimples is kept at 15 mm (constant) for all the studies performed. The Reynolds number of the flow is selected in the turbulent regime ranging from 9350 to 23 000 and the concentration of the nanofluid is taken in the range of 0.1–1%. It has been found that the heat transfer rate has improved significantly in dimpled radiator tube on the expense of pumping power. Furthermore, the heat transfer rate also increases with increase in nanoparticle concentration from 0.1% to 1.0%. The highest heat transfer enhancement of 79% is observed at Reynolds number 9350, while least enhancement of 18% is observed for Reynolds number of 23 000.

17

Nanofluid assistance in machining processes – properties, mechanisms and applications: a review

Grzesik Wit

Journal of Machine Engineering

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2021

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Vol. 21, No. 2

75--90

EN

A special group of hybrid assisted processes termed media-assisted processes which apply liquid media with special additives in the form of nanoparticles supplied to the cutting zone is overviewed. Special attention is paid to minimum quantity lubrication (MQL) technique with the use of nanofluids. In this review paper some important thermal and tribological effects resulting from the applications of various nanoparticles are outlined and compared. The MQL-nano cutting fluid mechanisms (rolling and ploughing) are described. In particular, some important quantitative effects concerning thermal and tribological behaviour of the cutting process as well as surface quality are presented.

18

Effects of rotation on Jeffrey nanofluid flow saturated by a porous medium

Rana Gian C.

Journal of Applied Mathematics and Computational Mechanics

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2021

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Vol. 20, nr 3

17--29

EN

In this paper, the effects of rotation on a Jeffery nanofluid flow in a porous medium which is heated from below is studied. Darcy model is employed for porous medium and the Jeffrey fluid model is used as a base fluid. The Navier-Stokes equations of motion of fluid are modified under the influence of the Jeffrey parameter, naoparticles and rotation. The basic perturbation technique based on normal modes is applied to derive the dispersion relation for a Rayleigh number. The effects of the Taylor number, Jeffrey parameter, Lewis number, modified diffusivity ratio, nanoparticles Rayleigh number and medium porosity on the stationary convection of the physical system have been analyzed analytically and graphically. It is observed that the rotation parameter has a stabilising influence for both bottom/top-heavy configurations.

19

Analysis of transient natural convective flow of a nanofluid in a vertical tube

Jha Basant K., Chitumu Ali J., Oni Michael O.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 2

31--46

EN

An analysis into the transient natural convective flow of a nanofluid in a vertical tube is made. The governing equations of momentum, heat transfer and nanoparticle volume fraction are deduced, and the influence of the thermophoresis parameter and Brownian motion is incorporated. By direct integration and variation of the parameter, analytical solutions are obtained for flow formation and heat/mass transfer at steady-state. On the other hand, due to the complexity of same problem at transient state, a numerical solution is used to solve the discretized equations of motion using the implicit finite difference technique. The influence of the thermophoresis parameter and Brownian motion is noted and well discussed. For accuracy check, a numerical comparison is made between the steady state and transient state solution at large time; this comparison gives an excellent agreement. The role of various principal parameters on velocity profile, temperature, concentration of nanoparticles, Sherwood and Nusselt numbers are presented graphically and well discussed. It is noted that the buoyancy ratio decreases the fluid velocity significantly.

20

A revised model for the effect of nanoparticle mass flux on the thermal instability of a nanofluid layer

Alharbi Ozwah S., Abdullah Abdullah A.

Demonstratio Mathematica

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2021

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Vol. 54, nr 1

488--499

EN

A revised model of the nanoparticle mass flux is introduced and used to study the thermal instability of the Rayleigh-Benard problem for a horizontal layer of nanofluid heated from below. The motion of nanoparticles is characterized by the effects of thermophoresis and Brownian diffusion. The nanofluid layer is confined between two rigid boundaries. Both boundaries are assumed to be impenetrable to nanoparticles with their distribution being determined from a conservation condition. The material properties of the nanofluid are allowed to depend on the local volume fraction of nanoparticles and are modelled by non-constant constitutive expressions developed by Kanafer and Vafai based on experimental data. The results show that the profile of the nanoparticle volume fraction is of exponential type in the steady-state solution. The resulting equations of the problem constitute an eigenvalue problem which is solved using the Chebyshev tau method. The critical values of the thermal Rayleigh number are calculated for several values of the parameters of the problem. Moreover, the critical eigenvalues obtained were real-valued, which indicates that the mode of instability is via a stationary mode.