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Entropy
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Entropy Production in Turbulent Flow
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Entropy Production in Turbulent Flow

A special issue of Entropy (ISSN 1099-4300).

Deadline for manuscript submissions: closed (30 April 2019) | Viewed by 16802

Special Issue Editors

Dr. Vincenzo Bianco

E-Mail Website
Guest Editor
DIME/TEC, Division of Thermal Energy and Environmental Conditioning, University of Genoa, 16145 Genoa, Italy
Interests: energy efficiency; energy transition; energy economics; energy policy; sustainability
Special Issues, Collections and Topics in MDPI journals
Dr. Bernardo Buonomo

E-Mail Website
Guest Editor
Dipartimento di Ingegneria.Università degli Studi della Campania "Luigi Vanvitelli", Via Roma 29, 81031 Aversa (CE), Italy
Interests: entropy generation; convective heat transfer; heat transfer by nanofluids; thermal storage; heat transfer in porous media; heat transfer in microchannel
Special Issues, Collections and Topics in MDPI journals
Dr. Omid Mahian

E-Mail Website
Guest Editor
School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an 710049, China
Interests: solar energy systems; entropy generation and exergy analysis in energy systems; heat transfer in nanofluids; solar stills
Special Issues, Collections and Topics in MDPI journals
Dr. Anatoliy Khait

E-Mail Website
Guest Editor
1. Institute of Civil Engineering, Ural Federal University, 19 Mira St., 620002 Ekaterinburg, Russia
2. School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
Interests: computational fluid dynamics; heat transfer; water waves mechanics
Dr. Mattia De Rosa

E-Mail Website
Guest Editor
1. School of Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4, Ireland
2. UCD Energy Institute, University College Dublin, Belfield, Dublin 4, Ireland
Interests: energy efficiency; sustainability; buildings; renewable energies; smart technologies
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The importance of the study of turbulent flows is well known, as they are typical in industrial applications. There are many studies in the literature dealing with the analysis of turbulent flows for different configurations, on the other hand many aspects need further investigation.

The focus of this special issue is on the study of the entropy generation in turbulent flows from the theoretical or applicative point of views.

Entropy generation can be used as a practical framework for design and optimization of devices characterized by turbulent flows, in order to improve their efficiency, as in the case of combustion chambers, vortex tubes, turbulence promoters and porous media. This could be an area worth of investigation, in order to promote the utilization of entropy generation analysis in the engineering practice.

Furthermore, theoretical investigation is necessary to provide simple approaches for the estimation of entropy generation in numerical models, for example when turbulence models other than k-ɛ are taken into account.

These are only two examples of areas worth investigations and the present special issue is open to consider high quality papers dealing with other aspects of entropy production in turbulent flows.

Prof. Dr. Vincenzo Bianco
Dr. Bernardo Buonomo
Dr. Omid Mahian
Dr. Anatoliy Khait
Dr. Mattia De Rosa
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Entropy 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 2600 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

  • turbulent flow
  • entropy generation
  • irreversible processes
  • exergy
  • heat transfer
  • viscous flow
  • computational fluid dynamics
  • heat transfer in porous media
  • nanofluids
  • convection heat transfer
  • oceanic and terrestrial circulation
  • porous media
  • irreversible processes
  • oceanic
  • terrestrial circulation

Published Papers (5 papers)

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Research

21 pages, 3504 KiB  
Article
Entropy Generation of Forced Convection during Melting of Ice Slurry
by Beata Niezgoda-Żelasko
Entropy 2019, 21(5), 514; https://doi.org/10.3390/e21050514 - 21 May 2019
Cited by 2 | Viewed by 3110
Abstract
This paper looks at entropy generation during ice slurry flow in straight pipes and typical heat exchanger structures used in refrigeration and air-conditioning technology. A dimensionless relationship was proposed to determine the interdependency between flow velocity and the volume fraction of ice, for [...] Read more.
This paper looks at entropy generation during ice slurry flow in straight pipes and typical heat exchanger structures used in refrigeration and air-conditioning technology. A dimensionless relationship was proposed to determine the interdependency between flow velocity and the volume fraction of ice, for which the entropy generation rates were at the minimum level in the case of non-adiabatic ice slurry flow. For pipe flow, the correlation between the minimum entropy generation rate and the overall enhancement efficiency was analyzed. As regards heat exchange processes in heat exchangers, the authors analyzed the relationship between the minimum entropy generation rate and the heat exchange surface area and exchanger efficiency. Full article
(This article belongs to the Special Issue Entropy Production in Turbulent Flow)
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17 pages, 4713 KiB  
Article
Heat Transfer and Entropy Generation Abilities of MWCNTs/GNPs Hybrid Nanofluids in Microtubes
by Ahmed A. Hussien, Mohd Z. Abdullah, Nadiahnor Md Yusop, Wael Al-Kouz, Ebrahim Mahmoudi and Mohammad Mehrali
Entropy 2019, 21(5), 480; https://doi.org/10.3390/e21050480 - 09 May 2019
Cited by 56 | Viewed by 3710
Abstract
Massive improvements in the thermophysical properties of nanofluids over conventional fluids have led to the rapid evolution of using multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in the field of heat transfer. In this study, the heat transfer and entropy generation abilities [...] Read more.
Massive improvements in the thermophysical properties of nanofluids over conventional fluids have led to the rapid evolution of using multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in the field of heat transfer. In this study, the heat transfer and entropy generation abilities of MWCNTs/GNPs hybrid nanofluids were explored. Experiments on forced convective flow through a brass microtube with 300 µm inner diameter and 0.27 m in length were performed under uniform heat flux. MWCNTs/GNPs hybrid nanofluids were developed by adding 0.035 wt.% GNPs to MWCNTs water-based nanofluids with mass fractions of 0.075–0.125 wt.%. The range of the Reynolds number in this experiment was maintained at Re = 200–500. Results showed that the conventional approach for predicting the heat transfer coefficient was applicable for microtubes. The heat transfer coefficient increased markedly with the use of MWCNTs and MWCNTs/GNPs nanofluids, with increased pressure dropping by 12.4%. Results further showed a reduction by 37.5% in the total entropy generation rate in microtubes for hybrid nanofluids. Overall, MWCNTs/GNPs hybrid nanofluids can be used as alternative fluids in cooling systems for thermal applications. Full article
(This article belongs to the Special Issue Entropy Production in Turbulent Flow)
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18 pages, 5038 KiB  
Article
Energy and Entropy in Turbulence Decompositions
by Václav Uruba
Entropy 2019, 21(2), 124; https://doi.org/10.3390/e21020124 - 29 Jan 2019
Cited by 7 | Viewed by 2923
Abstract
The role of energy and entropy in the decomposition of turbulent velocity flow-fields is shown in this paper. Decomposition methods based on the energy concept are taken into account—proper orthogonal decomposition (POD) and its extension bi-orthogonal decomposition (BOD). The methods are well known; [...] Read more.
The role of energy and entropy in the decomposition of turbulent velocity flow-fields is shown in this paper. Decomposition methods based on the energy concept are taken into account—proper orthogonal decomposition (POD) and its extension bi-orthogonal decomposition (BOD). The methods are well known; however, various versions are used and the interpretation of results is not straightforward. To make this clearer, the specific definition of modes is suggested and specified; moreover, energy- and entropy-motivated views on the decomposed modes are presented. This concept could offer new possibilities in the physical interpretation of modes and in reduced-order modeling (ROM) strategy efficiency evaluation. Full article
(This article belongs to the Special Issue Entropy Production in Turbulent Flow)
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13 pages, 1707 KiB  
Article
Optimal Design of Nanoparticle Enhanced Phan-Thien–Tanner Flow of a Viscoelastic Fluid in a Microchannel
by Mohammad Yaghoub Abdollahzadeh Jamalabadi
Entropy 2018, 20(12), 895; https://doi.org/10.3390/e20120895 - 22 Nov 2018
Viewed by 2524
Abstract
The excellent thermal characteristics of nanoparticles have increased their application in the field of heat transfer. In this paper, a thermophysical and geometrical parameter study is performed to minimize the total entropy generation of the viscoelastic flow of nanofluid. Entropy generation with respect [...] Read more.
The excellent thermal characteristics of nanoparticles have increased their application in the field of heat transfer. In this paper, a thermophysical and geometrical parameter study is performed to minimize the total entropy generation of the viscoelastic flow of nanofluid. Entropy generation with respect to volume fraction (<0.04), the Reynolds number (20,000–100,000), and the diameter of the microchannel (20–20,000 μm) with the circular cross-section under constant flux are calculated. As is shown, most of the entropy generation owes to heat transfer and by increasing the diameter of the channel, the Bejan number increases. The contribution of heat entropy generation in the microchannel is very poor and the major influence of entropy generation is attributable to friction. The maximum quantity of in-channel entropy generation happens in nanofluids with TiO2, CuO, Cu, and Ag nanoparticles, in turn, despite the fact in the microchannel this behavior is inverted, the minimum entropy generation occurs in nanofluids with CuO, Cu, Ag, and TiO2 nanoparticles, in turn. In the channel and microchannel for all nanofluids except water-TiO2, increasing the volume fraction of nanoparticles decreases entropy generation. In the channel and microchannel the total entropy generation increases by augmentation the Reynolds number. Full article
(This article belongs to the Special Issue Entropy Production in Turbulent Flow)
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19 pages, 3077 KiB  
Article
Entropy Production on the Gravity-Driven Flow with Free Surface Down an Inclined Plane Subjected to Constant Temperature
by Jaesung Lee
Entropy 2018, 20(4), 293; https://doi.org/10.3390/e20040293 - 17 Apr 2018
Cited by 1 | Viewed by 3256
Abstract
The long-wave approximation of a falling film down an inclined plane with constant temperature is used to investigate the volumetric averaged entropy production. The velocity and temperature fields are numerically computed by the evolution equation at the deformable free interface. The dynamics of [...] Read more.
The long-wave approximation of a falling film down an inclined plane with constant temperature is used to investigate the volumetric averaged entropy production. The velocity and temperature fields are numerically computed by the evolution equation at the deformable free interface. The dynamics of a falling film have an important role in the entropy production. When the layer shows an unstable evolution, the entropy production by fluid friction is much larger than that of the film with a stable flat interface. As the heat transfers actively from the free surface to the ambient air, the temperature gradient inside flowing films becomes large and the entropy generation by heat transfer increases. The contribution of fluid friction on the volumetric averaged entropy production is larger than that of heat transfer at moderate and high viscous dissipation parameters. Full article
(This article belongs to the Special Issue Entropy Production in Turbulent Flow)
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