Special Issue "Nanofluids and Their Applications"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Nanotechnology and Applied Nanosciences".

Deadline for manuscript submissions: closed (15 November 2018)

Special Issue Editors

Guest Editor
Prof. Guan Heng Yeoh

Mechanical and Manufacturing Engineering, University of New South Wales, Sydney NSW 2052, Australia
Website | E-Mail
Interests: Computational Fluid Dynamics; Numerical Heat and Mass Transfer; Turbulence modelling using Reynolds-Averaging and Large Eddy Simulation; Combustion, Radiation Heat Transfer, Soot Formation and Oxidation, Solid Pyrolysis in Fire Modelling; Fundamental studies in Multiphase Flows: Free Surface, Gas-Particle, Liquid-Particle, Gas-Liquid (bubbly and subcooled nucleate boiling), Freezing/Solidification and Liquid-Gas-Solid; Computational modelling of Magnetic Micro-particles in Mechanical Dampers; Computational modelling of Magnetic Drug Delivery and Targeting; Computational modelling of Nanofluids with Heat Transfer; Computational modelling of industrial systems of single-phase such as in HVAC (Heating, Ventilation and Air Conditioning); Computational modelling of industrial systems of multiphase flows (heat exchangers, boilers and nuclear reactors, cryogenics)
Guest Editor
Dr. Sherman Cheung

Mechanical and Automotive Engineering, RMIT University, Bundoora Victoria 3083, Australia
Website | E-Mail
Interests: Computational Fluid Dynamics; Fire Modelling; Gas-Liquid Bubbly Flows; Numerical Heat and Mass Transfer

Special Issue Information

Dear Colleagues,

Nanofluids are engineered colloidal suspensions of nanometer-sized particles in a base fluid of water, ethylene glycol or oil. Such fluids can be fundamentally characterized by Brownian agitation, in which they can then overcome the settling motion of the so-called nanoparticles due to gravity.

Nanofluids have been extensively used in a wide variety of engineering applications. For heat transfer processes, this has been primarily driven by the potential of developing fluids with significantly-increased conductive and convective heat transfer properties. Specific emphasis in boiling phenomena and absorption and conversion of radiation are some examples of the possible utilizations of nanofluids. Other non-heat transfer applications that have considered the use of nanofluids include emerging synthesis techniques, mass transport, optics, consumer goods, electronics, and surfaces and catalysts.

A stable nanofluid is theoretically possible, so long as the individual nanoparticles remain finely dispersed or the particle agglomerates remain small enough (usually <100 nanometers) in order to avoid large particle agglomerates from settling within the colloidal suspension. Maintaining this size is, however, the greatest challenge, since it is well known that nanoparticles have a tendency to agglomerate when they come into contact with each other.

This Special Issue is developed to review the current state-of-the-art of nanofluids due to the rapid advances and increasing control in nano-material fabrication techniques. Because of the complex behavior of nanofluids, fundamental and applied studies in nanofluids are welcome. Papers focusing on the expansion of nanofluid applications in diverse, multidisciplinary research and development are also welcomed. 

Prof. Guan Heng Yeoh
Assoc. Prof. Sherman Cheung
Guest Editors

Manuscript Submission Information

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Keywords

  • Thermo-physical properties
  • Smart cooling
  • Nanofluidics
  • Magnetic responsive nanoparticles
  • Plasmonic resonance nanoparticles
  • Nanolubricants

Published Papers (17 papers)

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Research

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Open AccessArticle Magnetic Field Effect on the Double Diffusive Natural Convection in Three-Dimensional Cavity Filled with Micropolar Nanofluid
Appl. Sci. 2018, 8(12), 2342; https://doi.org/10.3390/app8122342
Received: 15 September 2018 / Revised: 11 November 2018 / Accepted: 15 November 2018 / Published: 22 November 2018
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Abstract
This article presents a three-dimensional numerical investigation of heat and mass transfers and fluid flow in a cavity filled with an Al2O3/water micropolar fluid under uniform magnetic field. To solve the governing non-dimensional equations, Finite Volume Method (FVM) based [...] Read more.
This article presents a three-dimensional numerical investigation of heat and mass transfers and fluid flow in a cavity filled with an Al2O3/water micropolar fluid under uniform magnetic field. To solve the governing non-dimensional equations, Finite Volume Method (FVM) based on 3-D vorticity-vector potential formulation has been employed. The effects of various parameters such as buoyancy ratio (−2 ≤ N ≤ 0), Rayleigh number (103 ≤ Ra ≤ 105), Hartmann number (0≤ Ha≤ 60), nanoparticles volume fraction (0 ≤ φ ≤ 0.06) and micropolar material parameter (0≤ K≤ 5) on flow structure and on heat and mass transfers are presented. The results illustrate that for the micropolar nanofluid model, both heat and mass transfer rates and three-dimensional character of the flow are smaller when compared with the pure nanofluid model. It is also observed that increase and decrease in heat and mass transfer rates is experienced due to increase in Rayleigh number and Hartmann number, respectively. It is also noted that increase in vortex viscosity parameter reduces the average heat and mass transfer rates and is more evident when the magnetic field is imposed. Combined effects of magnetic field and nanoparticles volume fraction on heat and mass transfers are also explored. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Ethylene- and Propylene-Glycol Based Nanofluids: A Litterature Review on Their Thermophysical Properties and Thermal Performances
Appl. Sci. 2018, 8(11), 2311; https://doi.org/10.3390/app8112311
Received: 27 October 2018 / Revised: 13 November 2018 / Accepted: 15 November 2018 / Published: 20 November 2018
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Abstract
Nanofluids are considered a promising way to improve the heat transfer capability of base fluids. Water is the most commonly-used heat transfer fluid. However, in refrigeration systems, it may be necessary to mix water with either ethylene- or propylene-glycol to lower its freezing [...] Read more.
Nanofluids are considered a promising way to improve the heat transfer capability of base fluids. Water is the most commonly-used heat transfer fluid. However, in refrigeration systems, it may be necessary to mix water with either ethylene- or propylene-glycol to lower its freezing point and prevent from ice formation. In the same way, for car radiators or industrial heat exchangers, the boiling point of water can be pushed up by mixing it with glycol-based fluids. The increasing awareness of energy saving and industrial energy efficiency improvement results in the growing interest in ethylene- or propylene-glycol-based nanofluids for applications in various thermal systems. The present paper proposes an extensive review of the most recent and relevant experimental and numerical works on the thermophysical properties and performances of ethylene- or propylene-glycol-based nanofluids. Research perspectives are also provided with the long-term objective that these nanofluids be more widely considered in real industrial applications. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Unsteady Stagnation-Point Flow and Heat Transfer Over a Permeable Exponential Stretching/Shrinking Sheet in Nanofluid with Slip Velocity Effect: A Stability Analysis
Appl. Sci. 2018, 8(11), 2172; https://doi.org/10.3390/app8112172
Received: 26 September 2018 / Revised: 5 October 2018 / Accepted: 8 October 2018 / Published: 6 November 2018
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Abstract
A model of unsteady stagnation-point flow and heat transfer over a permeable exponential stretching/shrinking sheet with the presence of velocity slip is considered in this paper. The nanofluid model proposed by Tiwari and Das is applied where water with Prandtl number 6.2 has [...] Read more.
A model of unsteady stagnation-point flow and heat transfer over a permeable exponential stretching/shrinking sheet with the presence of velocity slip is considered in this paper. The nanofluid model proposed by Tiwari and Das is applied where water with Prandtl number 6.2 has been chosen as the base fluid, while three different nanoparticles are taken into consideration, namely Copper, Alumina, and Titania. The ordinary differential equations are solved using boundary value problem with fourth order accuracy (bvp4c) program in Matlab to find the numerical solutions of the skin friction and heat transfer coefficients for different parameters such as stretching/shrinking, velocity slip, nanoparticle volume fraction, suction/injection, and also different nanoparticles, for which the obtained results (dual solutions) are presented graphically. The velocity and temperature profiles are presented to show that the far field boundary conditions are asymptotically fulfilled, and validate the findings of dual solutions as displayed in the variations of the skin friction and heat transfer coefficients. The last part is to perform the stability analysis to determine a stable and physically-realizable solution. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Thermophysical Analysis of Water Based (Cu–Al2O3) Hybrid Nanofluid in an Asymmetric Channel with Dilating/Squeezing Walls Considering Different Shapes of Nanoparticles
Appl. Sci. 2018, 8(9), 1549; https://doi.org/10.3390/app8091549
Received: 11 June 2018 / Revised: 15 July 2018 / Accepted: 20 July 2018 / Published: 4 September 2018
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Abstract
An innovative concept of water-based Cu–Al2O3 hybrid nanofluid has been employed to investigate the behavior of flow and heat transfer inside a rectangular channel whose permeable walls experiences dilation or contraction in height. The transformed set of ordinary differential equations [...] Read more.
An innovative concept of water-based Cu–Al2O3 hybrid nanofluid has been employed to investigate the behavior of flow and heat transfer inside a rectangular channel whose permeable walls experiences dilation or contraction in height. The transformed set of ordinary differential equations is then solved by a well-known Runge–Kutta–Fehlberg algorithm. The analysis also includes three different shapes of copper nanocomposites, namely, platelet, cylinder and brick- shaped. The impact of various embedded parameters on the flow and heat transfer distributions have been demonstrated through the graphs. All the flow properties, temperature profile and rate of heat transfer at the walls are greatly influenced by the presence of copper nanoparticles. Furthermore, it was observed that the platelet shaped nanocomposites provide a better heat transfer ability as compared to the other shapes of nanoparticles. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Anomalous Increase in Specific Heat of Binary Molten Salt-Based Graphite Nanofluids for Thermal Energy Storage
Appl. Sci. 2018, 8(8), 1305; https://doi.org/10.3390/app8081305
Received: 30 June 2018 / Revised: 1 August 2018 / Accepted: 3 August 2018 / Published: 5 August 2018
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Abstract
An anomalous increase of the specific heat was experimentally observed in molten salt nanofluids using a differential scanning calorimeter. Binary carbonate molten salt mixtures were used as a base fluid, and the base salts were doped with graphite nanoparticles. Specific heat measurements of [...] Read more.
An anomalous increase of the specific heat was experimentally observed in molten salt nanofluids using a differential scanning calorimeter. Binary carbonate molten salt mixtures were used as a base fluid, and the base salts were doped with graphite nanoparticles. Specific heat measurements of the nanofluids were performed to examine the effects of the composition of two salts consisting of the base fluid. In addition, the effect of the nanoparticle concentration was investigated as the concentration of the graphite nanoparticles was varied from 0.025 to 1.0 wt %. Moreover, the dispersion homogeneity of the nanoparticles was explored by increasing amount of surfactant in the synthesis process of the molten salt nanofluids. The results showed that the specific heat of the nanofluid was enhanced by more than 30% in the liquid phase and by more than 36% in the solid phase at a nanoparticle concentration of 1 wt %. It was also observed that the concentration and the dispersion homogeneity of nanoparticles favorably affected the specific heat enhancement of the molten salt nanofluids. The dispersion status of graphite nanoparticles into the salt mixtures was visualized via scanning electron microscopy. The experimental results were explained according to the nanoparticle-induced compressed liquid layer structure of the molten salts. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessFeature PaperArticle The Effect of Gold Nanorods Clustering on Near-Infrared Radiation Absorption
Appl. Sci. 2018, 8(7), 1132; https://doi.org/10.3390/app8071132
Received: 21 May 2018 / Revised: 3 July 2018 / Accepted: 3 July 2018 / Published: 12 July 2018
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Abstract
In this paper, the plasmonic resonant absorption of gold nanorods (GNRs) and GNR solutions was studied both numerically and experimentally. The heat generation in clustered GNR solutions with various concentrations was measured by exposing them to Near Infrared (NIR) light in experiment. Correspondingly, [...] Read more.
In this paper, the plasmonic resonant absorption of gold nanorods (GNRs) and GNR solutions was studied both numerically and experimentally. The heat generation in clustered GNR solutions with various concentrations was measured by exposing them to Near Infrared (NIR) light in experiment. Correspondingly, calculations based on the discrete-dipole approximation (DDA) revealed the same relationship between the maximum absorption efficiency and the nanorod orientation for the incident radiation. Additionally, both the plasmonic wavelength and the maximum absorption efficiency of a single nanorod were found to increase linearly with increasing aspect ratio (for a fixed nanorod volume). The wavelength of the surface plasmonic resonance (SPR) was found to change when the gold nanorods were closely spaced. Specifically, both a shift and a broadening of the resonance peak were attained when the distance between the nanorods was set to about 50 nm or less. The absorbance spectra of suspended nanorods at various volume fractions also showed that the plasmonic wavelength of the nanorods solution was at 780 ± 10 nm, which was in good agreement with the computational predictions for coupled side-by-side nanorods. When heated by NIR light, the rate of increase for both the temperature of solution and the absorbed light diminished when the volume fraction of suspended nanorods reached a value of 1.24×106. This matches with expectations for a partially clustered suspension of nanorods in water. Overall, this study reveals that particle clustering should be considered to accurately gauge the heat generation of the GNR hyperthermia treatments. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Three-Dimensional Magnetohydrodynamic Mixed Convection Flow of Nanofluids over a Nonlinearly Permeable Stretching/Shrinking Sheet with Velocity and Thermal Slip
Appl. Sci. 2018, 8(7), 1128; https://doi.org/10.3390/app8071128
Received: 17 April 2018 / Revised: 23 May 2018 / Accepted: 6 June 2018 / Published: 12 July 2018
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Abstract
In this paper, the steady three-dimensional magnetohydrodynamic (MHD) mixed convection flow of nanofluids over a permeable vertical stretching/shrinking sheet with slip conditions is investigated in a numerical manner. As such, two types of nanofluids, Cu-water and Ag-water, had been considered. A similarity transformation [...] Read more.
In this paper, the steady three-dimensional magnetohydrodynamic (MHD) mixed convection flow of nanofluids over a permeable vertical stretching/shrinking sheet with slip conditions is investigated in a numerical manner. As such, two types of nanofluids, Cu-water and Ag-water, had been considered. A similarity transformation was employed to reduce the governing equations to ordinary differential equations, which were then solved numerically using the MATLAB (Matlab R2015a, MathWorks, Natick, MA, USA, 1984) programme bvp4c. The numerical solutions derived from the ordinary differential equations subjected to the associated boundary conditions, were obtained to represent the values of the mixed convection parameter. Dual (upper and lower branch) solutions were discovered in the opposing flow region of the mixed convection parameter. A stability analysis was carried out to prove that the upper branch solution was indeed stable, while the lower branch solution was unstable. The significant effects of the governing parameters on the reduced skin friction coefficients, the reduced local Nusselt number, as well as the velocity and temperature profiles, were presented graphically and discussed in detail. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Effect of Silica Nanoparticles on Fluid/Rock Interactions during Low Salinity Water Flooding of Chalk Reservoirs
Appl. Sci. 2018, 8(7), 1093; https://doi.org/10.3390/app8071093
Received: 11 June 2018 / Revised: 29 June 2018 / Accepted: 2 July 2018 / Published: 5 July 2018
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Abstract
The main objective of this work is to address the adsorption of Silica nanoparticles (NPs) dispersed in different brines on chalk surfaces and their effect on fluid/rock interaction. Isothermal static and dynamic adsorption on chalk are addressed here. Isothermal static adsorption showed increased [...] Read more.
The main objective of this work is to address the adsorption of Silica nanoparticles (NPs) dispersed in different brines on chalk surfaces and their effect on fluid/rock interaction. Isothermal static and dynamic adsorption on chalk are addressed here. Isothermal static adsorption showed increased adsorption of NPs at higher salinity. The tests were performed to cover wide range of injection scenarios with synthetic seawater (SSW) and low salinity water (LSW). The selected LSW composition here is based on 1:10 diluted SSW, which has shown to have superior performance compared to other ion compositions. The dynamic adsorption tests of NPs showed reduction of calcite dissolution of about 30% compared to LSW alone. That is, silica nanofluid hinders calcite dissolution i.e., has less effect on chalk matrix integrity which is a major concern in chalk reservoir, if low salinity is employed for enhanced oil recovery. Both scanning electron microscope images and pressure drop across the core during nanofluid injection indicated no throat blockage. Based on ion tracking and the monitored pH, the mechanism(s) for NP adsorption/desorption are suggested. The results from this study suggests a synergy wherein adding relatively small amount of silica NPs can improve the performance of low salinity floods. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Measurement and Quantification of Effective Slip Length at Solid–Liquid Interface of Roughness-Induced Surfaces with Oleophobicity
Appl. Sci. 2018, 8(6), 931; https://doi.org/10.3390/app8060931
Received: 16 May 2018 / Revised: 28 May 2018 / Accepted: 29 May 2018 / Published: 5 June 2018
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Abstract
Boundary conditions of the liquid–solid interface of micro/nano fluid flow are of great interest, as slippage is linked with decreased drag. However, previous studies have seldom included a systematic analysis of the effect of roughness on the measurement and quantification of slip length. [...] Read more.
Boundary conditions of the liquid–solid interface of micro/nano fluid flow are of great interest, as slippage is linked with decreased drag. However, previous studies have seldom included a systematic analysis of the effect of roughness on the measurement and quantification of slip length. For the measurement of slip length using atomic force microscopy (AFM), which is believed to be the most accurate method, a theoretical description of the drainage of thin liquid films between sphere and surface, with realistic roughness, is yet to be published. This study focuses on the measurement and quantification of slip length on rough surfaces immersed in liquids, based on AFM and laser confocal scanning microscopy. A reformulation of the boundary condition is presented, taking into account the effect of surface roughness. The correction to the effective slip length is analyzed, then surfaces with various degrees of spacing roughness Rsm were fabricated. Quantitative analysis of the effective slip length is presented. Results show that the corrected effective slip length remains constant with increased spacing roughness Rsm of surfaces. The results are discussed for the coagulation process of colloids and measurement of slip lengths on roughness-induced surfaces with AFM. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Stability Analysis of Mixed Convection Flow towards a Moving Thin Needle in Nanofluid
Appl. Sci. 2018, 8(6), 842; https://doi.org/10.3390/app8060842
Received: 9 April 2018 / Revised: 23 April 2018 / Accepted: 24 April 2018 / Published: 23 May 2018
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Abstract
The problem of steady laminar mixed convection flow and heat transfer past a moving vertical thin needle in nanofluid for both assisting and opposing cases is analyzed in this paper. Three types of nanoparticles including copper, titania and alumina are taken into consideration. [...] Read more.
The problem of steady laminar mixed convection flow and heat transfer past a moving vertical thin needle in nanofluid for both assisting and opposing cases is analyzed in this paper. Three types of nanoparticles including copper, titania and alumina are taken into consideration. The nonlinear ordinary differential equations for momentum and energy have been transformed by adopting the similarity transformation in linear form. The problem is solved numerically using an implemented package called bvp4c in MATLAB software. The numerical computations are carried out for various parameters of interest, which consists of the velocity ratio parameter, mixed convection parameter, nanoparticle volume fraction parameter and the needle size. A stability analysis of the solution is performed showing that the upper branch solution is stable, while the lower branch solution is unstable. Validation of the present work is done by comparing the current results with those available in the existing literature and found to be in excellent agreement. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle MHD Steady/Unsteady Porous Boundary Layer of Cu–Water Nanofluid with Micropolar Effect over a Permeable Surface
Appl. Sci. 2018, 8(5), 736; https://doi.org/10.3390/app8050736
Received: 5 March 2018 / Revised: 26 March 2018 / Accepted: 3 April 2018 / Published: 7 May 2018
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Abstract
This work provides a mathematical model for the cooling process of a moving surface, in the presence of a uniform external magnetic field and thermal radiation, through a porous medium by using a weak concentration micropolar nanofluid. The model—based on the conservation equations [...] Read more.
This work provides a mathematical model for the cooling process of a moving surface, in the presence of a uniform external magnetic field and thermal radiation, through a porous medium by using a weak concentration micropolar nanofluid. The model—based on the conservation equations of the unsteady case in the momentum and thermal boundary layer—takes into consideration the effect of the suction process. The conservation equations were transformed into ordinary differential equations using similar transformation techniques. The equations were solved numerically for the general case and analytically for the steady case. The rate of heat transfer, couple shear stress, and surface shear stress are deduced. We discuss the impact of these physical characteristics on the mechanical properties of the surface that will be cooled. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessFeature PaperArticle Stability Analysis of Stagnation-Point Flow in a Nanofluid over a Stretching/Shrinking Sheet with Second-Order Slip, Soret and Dufour Effects: A Revised Model
Appl. Sci. 2018, 8(4), 642; https://doi.org/10.3390/app8040642
Received: 27 March 2018 / Revised: 12 April 2018 / Accepted: 17 April 2018 / Published: 20 April 2018
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Abstract
The mathematical model of the two-dimensional steady stagnation-point flow over a stretching or shrinking sheet of nanofluid in the presence of the Soret and Dufour effects and of second-order slip at the boundary was considered in this paper. The partial differential equations were [...] Read more.
The mathematical model of the two-dimensional steady stagnation-point flow over a stretching or shrinking sheet of nanofluid in the presence of the Soret and Dufour effects and of second-order slip at the boundary was considered in this paper. The partial differential equations were transformed into the ordinary differential equations by applying a suitable similarity transformation. The numerical results were obtained by using bvp4c codes in Matlab. The skin friction coefficient, heat transfer coefficient, mass transfer coefficient, as well as the velocity, temperature, and concentration profiles were presented graphically for different values of slip parameters, Soret effect, Dufour effect, Brownian motion parameter, and thermophoresis parameter. A dual solution was obtained in this present paper. The presence of the slip parameters (first- and second-order slip parameters) was found to expand the range of solutions. However, the presence of the slip parameters led to a decrease in the skin friction coefficient, whereas the heat transfer coefficient increased. Besides that, a larger Soret effect (smallest Dufour effect) led to the decrement of the heat transfer coefficient. The effects of the Brownian motion and thermophoresis parameters on the heat transfer coefficient were also studied in this paper. A stability analysis was performed in this paper to verify the stability of the solutions obtained. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Effects of Nanoparticle Materials on Prebreakdown and Breakdown Properties of Transformer Oil
Appl. Sci. 2018, 8(4), 601; https://doi.org/10.3390/app8040601
Received: 14 March 2018 / Revised: 30 March 2018 / Accepted: 3 April 2018 / Published: 11 April 2018
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Abstract
In order to reveal the effects of nanoparticle materials on prebreakdown and breakdown properties of transformer oil, three types of nanoparticle materials, including conductive Fe3O4, semiconductive TiO2 and insulating Al2O3 nanoparticles, were prepared with the [...] Read more.
In order to reveal the effects of nanoparticle materials on prebreakdown and breakdown properties of transformer oil, three types of nanoparticle materials, including conductive Fe3O4, semiconductive TiO2 and insulating Al2O3 nanoparticles, were prepared with the same size and surface modification. An experimental study on the breakdown strength and prebreakdown streamer propagation characteristics were investigated for transformer oil and three types of nanofluids under positive lightning impulse voltage. The results indicate that the type of nanoparticle materials has a notable impact on breakdown strength and streamer propagation characteristics of transformer oil. Breakdown voltages of nanofluids are markedly increased by 41.3% and 29.8% respectively by the presence of Fe3O4 and TiO2 nanoparticles. Whereas a slight increase of only 7.4% is observed for Al2O3 nanofluid. Moreover, main discharge channels with thicker and denser branches are formed and the streamer propagation velocities are greatly lowered both in Fe3O4 and TiO2 nanofluids, while no obvious change appears in the propagation process of streamers in Al2O3 nanofluid in comparison with that in pure oil. The test results of trap characteristics reveal that the densities of shallow traps both in Fe3O4 and TiO2 nanofluids are much higher than that in Al2O3 nanofluid and pure oil, greatly reducing the distortion of the electric field. Thus, the propagations of positive streamers in the nanofluids are significantly suppressed by Fe3O4 and TiO2 nanoparticles, leading to the improvements of breakdown strength. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle A Stability Analysis on Mixed Convection Boundary Layer Flow along a Permeable Vertical Cylinder in a Porous Medium Filled with a Nanofluid and Thermal Radiation
Appl. Sci. 2018, 8(4), 483; https://doi.org/10.3390/app8040483
Received: 1 February 2018 / Revised: 23 February 2018 / Accepted: 25 February 2018 / Published: 23 March 2018
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Abstract
A study on mixed convection boundary layer flow with thermal radiation and nanofluid over a permeable vertical cylinder lodged in a porous medium is performed in this current research by considering groupings of a variety nanoparticles, consisting of copper (Cu), aluminium (Al2 [...] Read more.
A study on mixed convection boundary layer flow with thermal radiation and nanofluid over a permeable vertical cylinder lodged in a porous medium is performed in this current research by considering groupings of a variety nanoparticles, consisting of copper (Cu), aluminium (Al2O3) and titanium (TiO2). By using a method of similarity transformation, a governing set of ordinary differential equations has been reduced from the governing system of nonlinear partial differential equations, which are the values of selected parameters such as mixed convection parameter λ , nanoparticle volume fraction φ , radiation parameter Rd, suction parameter S, and curvature parameter ξ are solved numerically. From the numerical results, we observed that the involving of certain parameters ranges lead to the two different branches of solutions. We then performed a stability analysis by a bvp4c function (boundary value problem with fourth-order accuracy) to determine the most stable solution between these dual branches and the respective solutions. The features have been discussed in detail. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle Mathematical Models of Electro-Magnetohydrodynamic Multiphase Flows Synthesis with Nano-Sized Hafnium Particles
Appl. Sci. 2018, 8(2), 275; https://doi.org/10.3390/app8020275
Received: 4 January 2018 / Revised: 28 January 2018 / Accepted: 7 February 2018 / Published: 12 February 2018
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Abstract
The multiphase fluid flow under the influence of electro-magnetohydrodynamics (EHD) is investigated in this study. The base fluid contains hafnium particles. Two illustrative models namely fluid phase and particulate phase are considered for three different geometries having great importance in both industrial and [...] Read more.
The multiphase fluid flow under the influence of electro-magnetohydrodynamics (EHD) is investigated in this study. The base fluid contains hafnium particles. Two illustrative models namely fluid phase and particulate phase are considered for three different geometries having great importance in both industrial and mechanical usage. The impact of pertinent parameters from different aspects is illustrated graphically with requisite discussion keeping in view their physical aspects. The stream lines are also erected to highlight their physical importance regarding the flow patterns. In addition, the paper is terminated by making a comparison with the existing literature as a limiting case of considered problem to confirm the validations of achieved results and hence found in excellent agreement. This model can be used to design and engineer for nozzle or diffuser type of injectors in the latest models of automobiles to improve their performance and reduce the consumption of fuel. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Open AccessArticle The Combined Magneto Hydrodynamic and Electric Field Effect on an Unsteady Maxwell Nanofluid Flow over a Stretching Surface under the Influence of Variable Heat and Thermal Radiation
Appl. Sci. 2018, 8(2), 160; https://doi.org/10.3390/app8020160
Received: 10 December 2017 / Revised: 12 January 2018 / Accepted: 17 January 2018 / Published: 24 January 2018
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Abstract
The manuscript is a presentation of the combined effect of magnetic and electric field on unsteady flow of Maxwell nanofluid over a stretching surface with thermal radiations. The flow of Maxwell nanofluid is assumed to be in an unsteady state. The basic governing [...] Read more.
The manuscript is a presentation of the combined effect of magnetic and electric field on unsteady flow of Maxwell nanofluid over a stretching surface with thermal radiations. The flow of Maxwell nanofluid is assumed to be in an unsteady state. The basic governing equations changed to a group of differential equations, using proper similarity variables. The obtained modeled equations are nonlinear and coupled. An optimal approach is used to acquire the solution of the modeled problem analytically. The effects of electric field, magnetic field and thermal radiations on Maxwell nanofluid are the main focus in this study. The impact of the Skin friction on velocity profile, Nusselt number on temperature profile and Sherwood number on concentration profile are studied numerically. The influential behavior of the unsteady parameter λ , magnetic parameter M , electric parameter E , radiation parameter R d , Maxwell parameter β , thermophoresis parameter N t , Prandtl number Pr , Schmidt number S c , space dependent coefficient A and temperature dependent coefficient B on the velocity f ( h ) , concentration ϕ ( η ) and temperature θ ( η ) are analyzed and studied. The consequences are drawn graphically to see the physical significance of the problem. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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Review

Jump to: Research

Open AccessReview Preparation Techniques of TiO2 Nanofluids and Challenges: A Review
Appl. Sci. 2018, 8(4), 587; https://doi.org/10.3390/app8040587
Received: 10 February 2018 / Revised: 16 March 2018 / Accepted: 26 March 2018 / Published: 8 April 2018
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Abstract
Titanium dioxide (TiO2) has been used extensively because of its unique thermal and electric properties. Different techniques have been used for the preparation of TiO2 nanofluids which include single-step and two-step methods. In the natural world, TiO2 exists in [...] Read more.
Titanium dioxide (TiO2) has been used extensively because of its unique thermal and electric properties. Different techniques have been used for the preparation of TiO2 nanofluids which include single-step and two-step methods. In the natural world, TiO2 exists in three different crystalline forms as anatase, brookite, and rutile. Nanoparticles are not used directly in many heat transfer applications, and this provides a major challenge to researchers to advance towards stable nanofluid preparation methods. The primary step involved in the preparation of nanofluid is the production of nano-sized solid particles by using a suitable technique, and then these particles are dispersed into base fluids like oil, water, paraffin oil or ethylene glycol. However, nanofluid can also be prepared directly by using a liquid chemical method or vapor deposition technique (VDT). Nanofluids are mostly used in heat transfer applications and the size and cost of the heat transfer device depend upon the working fluid properties, thus, in the past decade scientists have made great efforts to formulate stable and cost-effective nanofluids with enhanced thermophysical properties. This review focuses on the different synthesis techniques and important physical properties (thermal conductivity and viscosity) that need to be considered very carefully during the preparation of TiO2 nanofluids for desired applications. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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