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Rheological Study of Nanofluids
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Rheological Study of Nanofluids

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Materials Processes".

Deadline for manuscript submissions: closed (15 September 2021) | Viewed by 21559

Special Issue Editor

Prof. Dr. Francisco J. Rubio-Hernández

E-Mail Website
Guest Editor
Departamento de Física Aplicada II, Universidad de Málaga, Escuela de Ingenierías Industriales, C/ Doctor Ortiz Ramos s/n, 29071 Málaga, Spain
Interests: colloidal suspensions rheology; thixotropy; shear-thickening; non-linear viscoelasticity; electrorheology; electroviscous effects

Special Issue Information

Dear Colleagues,

Nanofluids are suspensions of nano-metric-sized solid particles dispersed in liquid media. Although colloidal interactions determine the stability of these fluids against sedimentation, hydrodynamic forces are also decisive for the flow behavior of nanofluids.
Science usually precedes effective engineering applications. This is especially applicable to nanofluids considering the broad interest, initiated at the beginning of the new century, to find useful applications. Some of which are related to solar energy, heat transfer, biomedicine, automotive, mass transfer, lubricants, or smart fluids.
In most of these applications, the flow behavior of nanofluids should be well characterized. On the other hand, as nanofluids are non-Newtonian, showing shear-thinning, shear-thickening, or viscoplastic behavior depending on the shear forces they support, this task is clearly justified.
The aim of this Special Issue is to provide a state of the art on the rheological behavior of nanofluids considering the possible correlations between rheological and relevant properties for applications of nanofluids.

Dr. Francisco J. Rubio-Hernández
Guest Editor

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 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

  • Nanofluids
  • Rheology
  • Colloidal suspensions
  • Non-Newtonian nanofluids

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Published Papers (6 papers)

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Research

18 pages, 28337 KiB  
Article
A Molecular Dynamics Study of Heat Transfer Enhancement during Phase Change from a Nanoengineered Solid Surface
by A. K. M. Monjur Morshed, Muhammad Rubayat Bin Shahadat, Md. Rakibul Hasan Roni, Ahmed Shafkat Masnoon, Saif Al-Afsan Shamim and Titan C. Paul
Processes 2021, 9(4), 715; https://doi.org/10.3390/pr9040715 - 18 Apr 2021
Cited by 3 | Viewed by 3508
Abstract
This study investigates the enhancement of the rate of evaporation from a nanoengineered solid surface using non-equilibrium molecular dynamics simulation. Four different types of surface modifications were introduced to examine the thermal transportation behavior. The surface modification includes: (1) transformation of surface wetting [...] Read more.
This study investigates the enhancement of the rate of evaporation from a nanoengineered solid surface using non-equilibrium molecular dynamics simulation. Four different types of surface modifications were introduced to examine the thermal transportation behavior. The surface modification includes: (1) transformation of surface wetting condition from hydrophobic to hydrophilic, (2) implementing nanostructures on the smooth surface, (3) cutting nano slots on the smooth surface and (4) introducing nano-level surface roughness. Evaporation behavior from the same effective surface area was also studied. The simulation domain consisted of three distinct zones: solid base wall made of copper, a few layers of liquid argon, and a vapor zone made of argon. All the nano-level surface modifications were introduced on the solid base surface. The few layers of liquid argon representing the liquid zone of the domain take heat from the solid surface and get evaporated. Outside this solid and liquid zone, there is argon vapor. The simulation began at the initial time t = 0 ns and then was allowed to reach equilibrium. Immediately after equilibrium was achieved on all three-phase systems, the temperature of the solid wall was raised to a higher value. In this way, thermal transportation from the solid wall to liquid argon was established. As the temperature of the solid wall was high enough, the liquid argon tended to evaporate. From the simulation results, it is observed that during the transformation from hydrophobic to hydrophilic conditions, enhancement of evaporation takes place due to the improvement of thermal transportation behavior. At the nanostructure surface, the active nucleation sites and effective surface area increase which results in evaporation enhancement. With nano slots and nano-level surface roughness, the rate of evaporation increases due to the increase of solid-liquid contact area and effective surface area. Full article
(This article belongs to the Special Issue Rheological Study of Nanofluids)
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16 pages, 4401 KiB  
Article
Heat Transfer and Rheological Behavior of Fumed Silica Nanofluids
by A.I. Gómez-Merino, J.J. Jiménez-Galea, F.J. Rubio-Hernández, J.L. Arjona-Escudero and I.M. Santos-Ráez
Processes 2020, 8(12), 1535; https://doi.org/10.3390/pr8121535 - 25 Nov 2020
Cited by 18 | Viewed by 3046
Abstract
The addition of nanoparticles to liquid media can improve thermomechanical properties of dispersants. This ability gives rise to the development of multiple applications of nanofluids (NF) in branches so different as electronic and photonic devices or cosmetic industry. Logically, these applications require a [...] Read more.
The addition of nanoparticles to liquid media can improve thermomechanical properties of dispersants. This ability gives rise to the development of multiple applications of nanofluids (NF) in branches so different as electronic and photonic devices or cosmetic industry. Logically, these applications require a good control of heat transfer and flow properties. Moreover, if we consider the necessity to optimize industrial processes in which NF take part, it is necessary to obtain possible relationships between both physical mechanisms. Specifically, in this work, a study about thermal conductivity and rheological behavior of fumed silica suspensions in polypropylene glycol (PPG400) and polyethylene glycol (PEG200) was performed. The study of these two suspensions is interesting because the flow behaviors are very dissimilar (while the fumed silica in PEG200 suspension is viscoplastic, the fumed silica in PPG400 suspension shows shear-thickening behavior between two shear-thinning regions), despite the addition of fumed silica producing similar enhancement of the relative thermal conductivity in both liquid phases. The more outstanding contribution of this work lies in the combination of rheological and conductivity measurements to deepen in the understanding of the heat transfer phenomenon in NF. The combination of rheological together with thermal conductivity measurements have permitted establishing the mechanisms of liquid layering and aggregate formation as the more relevant in the heat transfer of these silica fumed suspensions. Full article
(This article belongs to the Special Issue Rheological Study of Nanofluids)
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17 pages, 3501 KiB  
Article
Preliminary Insights into Electro-Sensitive Ecolubricants: A Comparative Analysis Based on Nanocelluloses and Nanosilicates in Castor Oil
by Moisés García-Morales, Samuel D. Fernández-Silva, Claudia Roman, Marius A. Olariu, Maria T. Cidade and Miguel A. Delgado
Processes 2020, 8(9), 1060; https://doi.org/10.3390/pr8091060 - 1 Sep 2020
Cited by 19 | Viewed by 2449
Abstract
The newest generation of lubricants needs to adapt to stricter environmental policies. Simple and sustainable formulations with tunable rheological properties under the action of electric potentials may be the key. The present research explored the feasibility of producing electro-sensitive ecolubricants based on nanocellulose [...] Read more.
The newest generation of lubricants needs to adapt to stricter environmental policies. Simple and sustainable formulations with tunable rheological properties under the action of electric potentials may be the key. The present research explored the feasibility of producing electro-sensitive ecolubricants based on nanocellulose (crystalline and fibrillar) or nanoclay (Cloisite 15A montmorillonite and halloysite nanotubes) dispersions in castor oil, at concentrations that ranged from 2 to 6 wt.%. Broadband dielectric spectroscopy (BDS) measurements allowed for a first estimate on the electro-responsive potential of the nanofluids. The nanocelluloses and the montmorillonite suspensions presented a relaxation event in the dielectric loss, ε″, centered at ca. 2–4 kHz, which is related to interfacial polarization. Moreover, their actual electro-rheological (ER) effect under high electric potentials up to 4 kV/mm was assessed by determining the magnitude of the yield stress from steady flow curves at 25 °C. It was found that the nanocelluloses and the montmorillonite showed an enhancement of three orders of magnitude in their yield stress values at 4 kV/m. This enhancement was much greater than in the halloysite nanoclay, which did not exhibit any polarization). This is the starting point for the development of environmentally friendly ER lubricating fluids, based on nanocellulose and montmorillonites (layered nanosilicates), which might assist in reducing the friction and wear through the application of controlled electric fields. Full article
(This article belongs to the Special Issue Rheological Study of Nanofluids)
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11 pages, 3025 KiB  
Article
Extensional Magnetorheology as a Tool for Optimizing the Formulation of Ferrofluids in Oil-Spill Clean-Up Processes
by José Hermenegildo García-Ortiz and Francisco José Galindo-Rosales
Processes 2020, 8(5), 597; https://doi.org/10.3390/pr8050597 - 17 May 2020
Cited by 6 | Viewed by 2976
Abstract
In this study, we propose a new way of optimising the formulation of ferrofluids for oil-spill clean-up processes, based on the rheological behaviour under extensional flow and magnetic fields. Different commercial ferrofluids (FFs), consisting of a set of six ferrofluids with different magnetic [...] Read more.
In this study, we propose a new way of optimising the formulation of ferrofluids for oil-spill clean-up processes, based on the rheological behaviour under extensional flow and magnetic fields. Different commercial ferrofluids (FFs), consisting of a set of six ferrofluids with different magnetic saturation and particle concentration, were characterised in a Capillary Break-Up Extensional Rheometer (CaBER) equipped with two magnetorheological cells that allow imposing a homogeneous and tunable magnetic field either parallel or perpendicular to the flow direction. The filament thinning process with different intensities and orientation of the magnetic field with respect to the flow direction was analysed, and the results showed that the perpendicular configuration did not have a significant effect on the behaviour of the ferrofluids, as in shear magnetorheometry. However, the parallel configuration allowed to determine that the formulation of ferrofluids for oil-spill cleaning processes should consist of a 4% vol concentration of magnetic nanoparticles with a magnetic saturation of M s > 20 mT. Full article
(This article belongs to the Special Issue Rheological Study of Nanofluids)
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17 pages, 6510 KiB  
Article
Dual Solutions and Stability Analysis of Magnetized Hybrid Nanofluid with Joule Heating and Multiple Slip Conditions
by Liang Yan, Sumera Dero, Ilyas Khan, Irshad Ali Mari, Dumitru Baleanu, Kottakkaran Sooppy Nisar, El-Sayed M. Sherif and Hany S. Abdo
Processes 2020, 8(3), 332; https://doi.org/10.3390/pr8030332 - 12 Mar 2020
Cited by 64 | Viewed by 3632
Abstract
This paper investigates the steady, two dimensional, and magnetohydrodynamic flow of copper and alumina/water hybrid nanofluid on a permeable exponentially shrinking surface in the presence of Joule heating, velocity slip, and thermal slip parameters. Adopting the model of Tiwari and Das, the mathematical [...] Read more.
This paper investigates the steady, two dimensional, and magnetohydrodynamic flow of copper and alumina/water hybrid nanofluid on a permeable exponentially shrinking surface in the presence of Joule heating, velocity slip, and thermal slip parameters. Adopting the model of Tiwari and Das, the mathematical formulation of governing partial differential equations was constructed, which was then transformed into the equivalent system of non-linear ordinary differential equations by employing exponential similarity transformation variables. The resultant system was solved numerically using the BVP4C solver in the MATLAB software. For validation purposes, the obtained numerical results were compared graphically with those in previous studies, and found to be in good agreement, as the critical points are the same up to three decimal points. Based on the numerical results, it was revealed that dual solutions exist within specific ranges of the suction and magnetic parameters. Stability analysis was performed on both solutions in order to determine which solution(s) is/are stable. The analysis indicated that only the first solution is stable. Furthermore, it was also found that the temperature increases in both solutions when the magnetic parameter and Eckert number are increased, while it reduces as the thermal slip parameter rises. Furthermore, the coefficient of skin friction and the heat transfer rate increase for the first solution when the magnetic and the suction parameters are increased. Meanwhile, no change is noticed in the boundary layer separation for the various values of the Eckert number in the heat transfer rate. Full article
(This article belongs to the Special Issue Rheological Study of Nanofluids)
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21 pages, 9930 KiB  
Article
Study of Activation Energy on the Movement of Gyrotactic Microorganism in a Magnetized Nanofluids Past a Porous Plate
by Muhammad Mubashir Bhatti, Anwar Shahid, Tehseen Abbas, Sultan Z Alamri and Rahmat Ellahi
Processes 2020, 8(3), 328; https://doi.org/10.3390/pr8030328 - 11 Mar 2020
Cited by 127 | Viewed by 5013
Abstract
The present study deals with the swimming of gyrotactic microorganisms in a nanofluid past a stretched surface. The combined effects of magnetohydrodynamics and porosity are taken into account. The mathematical modeling is based on momentum, energy, nanoparticle concentration, and microorganisms’ equation. A new [...] Read more.
The present study deals with the swimming of gyrotactic microorganisms in a nanofluid past a stretched surface. The combined effects of magnetohydrodynamics and porosity are taken into account. The mathematical modeling is based on momentum, energy, nanoparticle concentration, and microorganisms’ equation. A new computational technique, namely successive local linearization method (SLLM), is used to solve nonlinear coupled differential equations. The SLLM algorithm is smooth to establish and employ because this method is based on a simple univariate linearization of nonlinear functions. The numerical efficiency of SLLM is much powerful as it develops a series of equations which can be subsequently solved by reutilizing the data from the solution of one equation in the next one. The convergence was improved through relaxation parameters in the study. The accuracy of SLLM was assured through known methods and convergence analysis. A comparison of the proposed method with the existing literature has also been made and found an excellent agreement. It is worth mentioning that the successive local linearization method was found to be very stable and flexible for resolving the issues of nonlinear magnetic materials processing transport phenomena. Full article
(This article belongs to the Special Issue Rheological Study of Nanofluids)
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