Special Issue "Lubrication Flows"

A special issue of Fluids (ISSN 2311-5521). This special issue belongs to the section "Non-Newtonian and Complex Fluids".

Deadline for manuscript submissions: closed (15 October 2021).

Special Issue Editor

Prof. Dr. Lorenzo Fusi
E-Mail Website
Guest Editor
Dipartimento di Matematica e Informatica “U. Dini”, Viale Morgagni 67/a, 50134 Firenze, Italy
Interests: fluid mechanics; visco-plastic flows; lubrication; stability analysis; free boundary problems

Special Issue Information

Dear Colleagues,

This Special Issue of Fluids is dedicated to the fluid mechanics of lubrication flows. Lubrication flows are ubiquitous in nature and technological applications. The main feature of these flows is the presence of a characteristic length that is markedly smaller than the others, so that a parameter describing the small aspect ratio can be defined. The governing equations can be expanded by means of perturbation series in powers of the small parameter and different approximations can be obtained depending on the chosen order of approximation. This procedure allows one to find analytical solutions and, when this is not possible, to greatly reduce the complexity of the related numerical problem.

With this Special Issue, Fluids invites manuscripts of original research that present experimental, theoretical, and numerical results related to “lubrication flows”. We aim to bring together researchers active on this topic to provide an overview of the state of the art in current investigations on lubrication flows and their analysis and modeling.

Prof. Dr. Lorenzo Fusi
Guest Editor

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 papers will be 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. Fluids 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 1600 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

  • lubrication flows 
  • perturbation analysis 
  • asymptotic expansion 
  • analytical solutions 
  • Newtonian and non-Newtonian fluids 
  • stability analysis 
  • computational methods 
  • Hele-Shaw flows

Published Papers (3 papers)

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Research

Article
Numerical Bifurcation Analysis of a Film Flowing over a Patterned Surface through Enhanced Lubrication Theory
Fluids 2021, 6(11), 405; https://doi.org/10.3390/fluids6110405 - 09 Nov 2021
Viewed by 246
Abstract
The bifurcation analysis of a film falling down an hybrid surface is conducted via the numerical solution of the governing lubrication equation. Instability phenomena, that lead to film breakage and growth of fingers, are induced by multiple contamination spots. Contact angles up to [...] Read more.
The bifurcation analysis of a film falling down an hybrid surface is conducted via the numerical solution of the governing lubrication equation. Instability phenomena, that lead to film breakage and growth of fingers, are induced by multiple contamination spots. Contact angles up to 75 are investigated due to the full implementation of the free surface curvature, which replaces the small slope approximation, accurate for film slope lower than 30. The dynamic contact angle is first verified with the Hoffman–Voinov–Tanner law in case of a stable film down an inclined plate with uniform surface wettability. Then, contamination spots, characterized by an increased value of the static contact angle, are considered in order to induce film instability and several parametric computations are run, with different film patterns observed. The effects of the flow characteristics and of the hybrid pattern geometry are investigated and the corresponding bifurcation diagram with the number of observed rivulets is built. The long term evolution of induced film instabilities shows a complex behavior: different flow regimes can be observed at the same flow characteristics under slightly different hybrid configurations. This suggest the possibility of controlling the rivulet/film transition via a proper design of the surfaces, thus opening the way for relevant practical application. Full article
(This article belongs to the Special Issue Lubrication Flows)
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Article
Performance Investigation of MQL Parameters Using Nano Cutting Fluids in Hard Milling
Fluids 2021, 6(7), 248; https://doi.org/10.3390/fluids6070248 - 06 Jul 2021
Cited by 1 | Viewed by 652
Abstract
Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalworking industry. Low machinability and high cutting temperature generated from the contact zone are the main obstacles that need to be solved in order to improve economic and technical efficiency but [...] Read more.
Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalworking industry. Low machinability and high cutting temperature generated from the contact zone are the main obstacles that need to be solved in order to improve economic and technical efficiency but still have to ensure environmental friendliness. The application of MQL method using nano cutting fluid is one of the suggested solutions to improve the cooling and lubricating performance of pure-MQL for machining difficult-to-cut materials. The main objective of this paper is to investigate the effects of nanofluid MQL (NFMQL) parameters including the fluid type, type of nanoparticles, air pressure and air flow rate on cutting forces and surface roughness in hard milling of 60Si2Mn hardened steel (50–52 HRC). Analysis of variance (ANOVA) was implemented to study the effects of investigated variables on hard machining performance. The most outstanding finding is that the main effects of the input variables and their interaction are deeply investigated to prove the better machinability and the superior cooling lubrication performance when machining under NFMQL condition. The experimental results indicate that the uses of smaller air pressure and higher air flow rate decrease the cutting forces and improve the surface quality. Al2O3 nanoparticles show the better results than MoS2 nanosheets. The applicability of soybean oil, a type of vegetable oil, is proven to be enlarged in hard milling by suspending nanoparticles, suitable for further studies in the field of sustainable manufacturing. Full article
(This article belongs to the Special Issue Lubrication Flows)
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Article
Squeeze Flow of Stress Power Law Fluids
Fluids 2021, 6(6), 194; https://doi.org/10.3390/fluids6060194 - 21 May 2021
Viewed by 749
Abstract
In this paper, we studied the squeeze flow between circular disks of a new class of fluids defined by an implicit relation referred to as stress power law fluids. The constitutive response of these fluids was written expressing the symmetric part of the [...] Read more.
In this paper, we studied the squeeze flow between circular disks of a new class of fluids defined by an implicit relation referred to as stress power law fluids. The constitutive response of these fluids was written expressing the symmetric part of the velocity gradient as a tensorial function of the Cauchy stress. We assumed that the aspect ratio between the gap separating the disks and the radius was small so that a lubrication expansion could be adopted. We wrote the general problem and looked for a solution that could be written in terms of the small aspect ratio parameter. We obtained a sequence of problems that could be solved iteratively at each order, and we focused on the leading and first order, deriving explicit expressions for the velocity field, stress, and pressure. Full article
(This article belongs to the Special Issue Lubrication Flows)
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