Special Issue "Rheology of Advanced Complex Fluids"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editor

Dr. Yannis Dimakopoulos
Website
Guest Editor
Department of Chemical Engineering, University of Patras, Patra, Greece
Interests: transport phenomena; non-newtonian fluid mechanics; rheology of complex fluids; hemorheology; biomechanics; large scales simulations; rheological modeling

Special Issue Information

Dear Colleagues,

The deformation and flow of polymeric or structured materials, which are also called complex fluids, is essentially controlled by their molecular chemistry and, consequently, their inherent rheological properties, their so-called material functions. Synthetic or biological structured fluids contain more than one phase, such as solid particles dispersed in a liquid, gas particles in foam, or an emulsion of immiscible liquids. On the other hand, polymeric and biopolymeric fluids have macromolecular structures. In the first case, the rheological behavior is dominated by the interactions of the constituents, while in the second one, intramolecular forces and chain entanglements play a crucial role. The continuous effort to predict and control the rheological response of complex fluids has led to a prolonged collaboration between industry, research institutes, and academia. The current Issue aims to host contributions related to measurements through experimental methods, characterization through advanced rheometric protocols, and the constitutive modeling and flow simulation of such fluids.

It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Dr. Yannis Dimakopoulos
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. Materials is an international peer-reviewed open access semimonthly 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 2000 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

  • polymer and biopolymer rheology
  • synthetic and biological structured fluids
  • constitutive modeling
  • experimental rheology
  • meso- and macro-scopic flow simulations
  • transport phenomena of complex fluids

Published Papers (5 papers)

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Research

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Open AccessArticle
Effect of Particle Specific Surface Area on the Rheology of Non-Brownian Silica Suspensions
Materials 2020, 13(20), 4628; https://doi.org/10.3390/ma13204628 - 16 Oct 2020
Abstract
Industrial formulations very often involve particles with a broad range of surface characteristics and size distributions. Particle surface asperities (roughness) and porosity increase particle specific surface area and significantly alter suspension rheology, which can be detrimental to the quality of the end product. [...] Read more.
Industrial formulations very often involve particles with a broad range of surface characteristics and size distributions. Particle surface asperities (roughness) and porosity increase particle specific surface area and significantly alter suspension rheology, which can be detrimental to the quality of the end product. We examine the rheological properties of two types of non-Brownian, commercial precipitated silicas, with varying specific surface area, namely PS52 and PS226, suspended in a non-aqueous solvent, glycerol, and compare them against those of glass sphere suspensions (GS2) with a similar size distribution. A non-monotonic effect of the specific surface area (S) on suspension rheology is observed, whereby PS52 particles in glycerol are found to exhibit strong shear thinning response, whereas such response is suppressed for glass sphere and PS226 particle suspensions. This behaviour is attributed to the competing mechanisms of particle–particle and particle–solvent interactions. In particular, increasing the specific surface area beyond a certain value results in the repulsive interparticle hydration forces (solvation forces) induced by glycerol overcoming particle frictional contacts and suppressing shear thinning; this is evidenced by the response of the highest specific surface area particles PS226. The study demonstrates the potential of using particle specific surface area as a means to tune the rheology of non-Brownian silica particle suspensions. Full article
(This article belongs to the Special Issue Rheology of Advanced Complex Fluids)
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Open AccessArticle
Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Description of the Model and Rheological Predictions
Materials 2020, 13(18), 4184; https://doi.org/10.3390/ma13184184 - 20 Sep 2020
Abstract
This work focuses on the advanced modeling of the thixotropic nature of blood, coupled with an elasto-visco-plastic formulation by invoking a consistent and validated model for TEVP materials. The proposed model has been verified for the adequate description of the rheological behavior of [...] Read more.
This work focuses on the advanced modeling of the thixotropic nature of blood, coupled with an elasto-visco-plastic formulation by invoking a consistent and validated model for TEVP materials. The proposed model has been verified for the adequate description of the rheological behavior of suspensions, introducing a scalar variable that describes dynamically the level of internal microstructure of rouleaux at any instance, capturing accurately the aggregation and disaggregation mechanisms of the RBCs. Also, a non-linear fitting is adopted for the definition of the model’s parameters on limited available experimental data of steady and transient rheometric flows of blood samples. We present the predictability of the new model in various steady and transient rheometric flows, including startup shear, rectangular shear steps, shear cessation, triangular shear steps and LAOS tests. Our model provides predictions for the elasto-thixotropic mechanism in startup shear flows, demonstrating a non-monotonic relationship of the thixotropic index on the shear-rate. The intermittent shear step test reveals the dynamics of the structural reconstruction, which in turn is associated with the aggregation process. Moreover, our model offers robust predictions for less examined tests such as uniaxial elongation, in which normal stress was found to have considerable contribution. Apart from the integrated modeling of blood rheological complexity, our implementation is adequate for multi-dimensional simulations due to its tensorial formalism accomplished with a single time scale for the thixotropic effects, resulting in a low computational cost compared to other TEVP models. Full article
(This article belongs to the Special Issue Rheology of Advanced Complex Fluids)
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Open AccessArticle
Simple, Accurate and User-Friendly Differential Constitutive Model for the Rheology of Entangled Polymer Melts and Solutions from Nonequilibrium Thermodynamics
Materials 2020, 13(12), 2867; https://doi.org/10.3390/ma13122867 - 26 Jun 2020
Cited by 3
Abstract
In a recent reformulation of the Marrucci-Ianniruberto constitutive equation for the rheology of entangled polymer melts in the context of nonequilibrium thermodynamics, rather large values of the convective constraint release parameter βccr had to be used in order for the model not [...] Read more.
In a recent reformulation of the Marrucci-Ianniruberto constitutive equation for the rheology of entangled polymer melts in the context of nonequilibrium thermodynamics, rather large values of the convective constraint release parameter βccr had to be used in order for the model not to violate the second law of thermodynamics. In this work, we present an appropriate modification of the model, which avoids the splitting of the evolution equation for the conformation tensor into an orientation and a stretching part. Then, thermodynamic admissibility simply dictates that βccr ≥ 0, thus allowing for more realistic values of βccr to be chosen. Moreover, and in view of recent experimental evidence for a transient stress undershoot (following the overshoot) at high shear rates, whose origin may be traced back to molecular tumbling, we have incorporated additional terms into the model accounting, at least in an approximate way, for non-affine deformation through a slip parameter ξ. Use of the new model to describe available experimental data for the transient and steady-state shear and elongational rheology of entangled polystyrene melts and concentrated solutions shows close agreement. Overall, the modified model proposed here combines simplicity with accuracy, which renders it an excellent choice for managing complex viscoelastic fluid flows in large-scale numerical calculations. Full article
(This article belongs to the Special Issue Rheology of Advanced Complex Fluids)
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Open AccessArticle
Viscoplastic Couette Flow in the Presence of Wall Slip with Non-Zero Slip Yield Stress
Materials 2019, 12(21), 3574; https://doi.org/10.3390/ma12213574 - 31 Oct 2019
Cited by 4
Abstract
The steady-state Couette flow of a yield-stress material obeying the Bingham-plastic constitutive equation is analyzed assuming that slip occurs when the wall shear stress exceeds a threshold value, the slip (or sliding) yield stress. The case of Navier slip (zero slip yield stress) [...] Read more.
The steady-state Couette flow of a yield-stress material obeying the Bingham-plastic constitutive equation is analyzed assuming that slip occurs when the wall shear stress exceeds a threshold value, the slip (or sliding) yield stress. The case of Navier slip (zero slip yield stress) is studied first in order to facilitate the analysis and the discussion of the results. The different flow regimes that arise depending on the relative values of the yield stress and the slip yield stress are identified and the various critical angular velocities defining those regimes are determined. Analytical solutions for all the regimes are presented and the implications for this important rheometric flow are discussed. Full article
(This article belongs to the Special Issue Rheology of Advanced Complex Fluids)
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Review

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Open AccessReview
Research Progress on the Collaborative Drag Reduction Effect of Polymers and Surfactants
Materials 2020, 13(2), 444; https://doi.org/10.3390/ma13020444 - 17 Jan 2020
Cited by 11
Abstract
Polymer additives and surfactants as drag reduction agents have been widely used in the field of fluid drag reduction. Polymer additives can reduce drag effectively with only a small amount, but they degrade easily. Surfactants have an anti-degradation ability. This paper categorizes the [...] Read more.
Polymer additives and surfactants as drag reduction agents have been widely used in the field of fluid drag reduction. Polymer additives can reduce drag effectively with only a small amount, but they degrade easily. Surfactants have an anti-degradation ability. This paper categorizes the mechanism of drag reducing agents and the influencing factors of drag reduction characteristics. The factors affecting the degradation of polymer additives and the anti-degradation properties of surfactants are discussed. A mixture of polymer additive and surfactant has the characteristics of high shear resistance, a lower critical micelle concentration (CMC), and a good drag reduction effect at higher Reynolds numbers. Therefore, this paper focuses more on a drag reducing agent mixed with a polymer and a surfactant, including the mechanism model, drag reduction characteristics, and anti-degradation ability. Full article
(This article belongs to the Special Issue Rheology of Advanced Complex Fluids)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. Title: Viscoplastic Couette flow in the presence of wall slip with non-zero slip yield stress
Authors:  Yiolanda Damianou, Pandelitsa Panaseti, Georgios G. Georgiou

2. Title: Advanced constitutive modeling of the thixotropic elasto-visco-plastic behavior of human blood (Part II): Steady-state blood flow in microtubes

Authors: K. Giannokostas, Y. Dimakopoulos, A. Anayiotos, J. Tsamopoulos

3. Title: Investigating the swollen state of Carbopol molecules in non-aqueous solvents through rheological characterization

Authors: Simona Migliozzi, Giovanni Meridiano, Luca Mazzei and Panagiota Angeli

4. Title: Effect of particle specific surface area on the rheology of non-Brownian silica suspensions

Authors: Anastasia Papadopoulou; Jurriaan J. Gillissen; Manish K Tiwari; Stavroula Balabani 

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