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Basilio Hazas M, Ziliotto F, Rolle M, Chiogna G. Linking mixing and flow topology in porous media: An experimental proof. Phys Rev E 2022; 105:035105. [PMID: 35428141 DOI: 10.1103/physreve.105.035105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Transport processes in porous media are controlled by the characteristics of the flow field which are determined by the porous material properties and the boundary conditions of the system. This work provides experimental evidence of the relation between mixing and flow field topology in porous media at the continuum scale. The setup consists of a homogeneously packed quasi-two-dimensional flow-through chamber in which transient flow conditions, dynamically controlled by two external reservoirs, impact the transport of a dissolved tracer. The experiments were performed at two different flow velocities, corresponding to Péclet numbers of 191 and 565, respectively. The model-based interpretation of the experimental results shows that high values of the effective Okubo-Weiss parameter, driven by the changes of the boundary conditions, lead to high rates of increase of the Shannon entropy of the tracer distribution and, thus, to enhanced mixing. The comparison between a hydrodynamic dispersion model and an equivalent pore diffusion model demonstrates that despite the spatial and temporal variability in the hydrodynamic dispersion coefficients, the Shannon entropy remains almost unchanged because it is controlled by the Okubo-Weiss parameter. Overall, our work demonstrates that under highly transient boundary conditions, mixing dynamics in homogeneous porous media can also display complex patterns and is controlled by the flow topology.
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Affiliation(s)
- Mónica Basilio Hazas
- Chair of Hydrology and River Basin Management, Technical University of Munich, Arcisstraße 21, 80333 Munich, Germany
| | - Francesca Ziliotto
- Chair of Hydrology and River Basin Management, Technical University of Munich, Arcisstraße 21, 80333 Munich, Germany
| | - Massimo Rolle
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Gabriele Chiogna
- Chair of Hydrology and River Basin Management, Technical University of Munich, Arcisstraße 21, 80333 Munich, Germany
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Xu J, Wang Y, Ma X. Phase distribution including a bubblelike region in supercritical fluid. Phys Rev E 2021; 104:014142. [PMID: 34412334 DOI: 10.1103/physreve.104.014142] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/02/2021] [Indexed: 11/07/2022]
Abstract
Pseudoboiling in supercritical fluid (SF) has been paid great attention in recent years. Available works mainly focus on thermodynamics analysis. Fewer studies were reported on the spatial time phase distribution. Here, SF is investigated in a multiphase fluid framework using molecular dynamics (MD) simulations. A simulation box contains 10 976 argon atoms, with periodic boundary conditions applied on all the box surfaces. Pressure and temperature are well controlled. Based on MD simulation results, an onset pseudoboiling temperature T^{-} and a termination pseudoboiling temperature T^{+} are defined using the neighboring molecules method, the radial distribution function method, and the two-body excess entropy method. The two transition temperatures divide the whole phase diagram into three regimes of liquidlike, two-phase-like (TPL), and gaslike, and the MD determined T^{-} and T^{+} well matched the thermodynamics-determined values. In the TPL regime, nanovoids are observed to have two distinct characteristics: (1) Particles are sparsely distributed to have gas density inside the void, but are densely populated to have liquid density outside the void. (2) Voids have a curved interface. These characteristics are very similar to bubble characteristics in subcritical pressure. Hence, voids in the supercritical state are called "bubblelike" in this paper. Nonlinear dynamics demonstrates chaotic behavior in the TPL regime, similar to the two-phase regime in the subcritical domain. The above findings give strong evidence that SF in the TPL regime consists of a mixture of bubblelike voids and surrounding liquids. Our work highlights the multiphase feature of a SF, hence, the well-established multiphase theory in subcritical pressures can be introduced to handle the complex SF.
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Affiliation(s)
- Jinliang Xu
- Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization, North China Electric Power University, Beijing, 102206, China.,Key Laboratory of Power Station Energy Transfer Conversion and System, North China Electric Power University, Ministry of Education, Beijing, 102206, China
| | - Yan Wang
- Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization, North China Electric Power University, Beijing, 102206, China
| | - Xiaojing Ma
- Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization, North China Electric Power University, Beijing, 102206, China
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Tuning Size and Morphology of mPEG- b-p(HPMA-Bz) Copolymer Self-Assemblies Using Microfluidics. Polymers (Basel) 2020; 12:polym12112572. [PMID: 33147743 PMCID: PMC7693845 DOI: 10.3390/polym12112572] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 12/14/2022] Open
Abstract
The careful design of nanoparticles, in terms of size and morphology, is of great importance to developing effective drug delivery systems. The ability to precisely tailor nanoparticles in size and morphology during polymer self-assembly was therefore investigated. Four poly(ethylene glycol)-b-poly(N-2-benzoyloxypropyl methacrylamide) mPEG-b-p(HPMA-Bz) block copolymers with a fixed hydrophilic block of mPEG 5 kDa and a varying molecular weight of the hydrophobic p(HPMA-Bz) block (A: 17.1, B: 10.0, C: 5.2 and D: 2.7 kDa) were self-assembled into nanoparticles by nanoprecipitation under well-defined flow conditions, using microfluidics, at different concentrations. The nanoparticles from polymer A, increased in size from 55 to 90 nm using lower polymer concentrations and slower flow rates and even polymer vesicles were formed along with micelles. Similarly, nanoparticles from polymer D increased in size from 35 to 70 nm at slower flow rates and also formed vesicles along with micelles, regardless of the used concentration. Differently, polymers B and C mainly self-assembled into micelles at the different applied flow rates with negligible size difference. In conclusion, this study demonstrates that the self-assembly of mPEG-b-p(HPMA-Bz) block copolymers can be easily tailored in size and morphology using microfluidics and is therefore an attractive option for further scaled-up production activities.
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Vagner SA, Patlazhan SA. Flow Structure and Mixing Efficiency of Viscous Fluids in Microchannel with a Striped Superhydrophobic Wall. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16388-16399. [PMID: 31692363 DOI: 10.1021/acs.langmuir.9b02884] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The peculiarities of a Newtonian fluid flow structure in microchannels with a striped superhydrophobic lower wall texture are studied by means of numerical modeling. In the Cassie-Baxter state, an oblique orientation of such a texture induces helicoidal streamlines with micro spirals. Such a flow structure favors the enhancement of fluid mixing efficiency, which can be quantified using the total root-mean-square deviation of streamlines from the microchannel axis. This characteristic was shown to be a nonmonotonic function of the striped texture tilt angle and to depend strongly on microchannel thickness. The mechanisms of micro and macro helicoidal flow structure formation are investigated, and the mixing quality of miscible fluids is estimated for various Peclet numbers and texture tilt angles. It was found that the striped superhydrophobic wall leads to a notable enhancement in the microchannel mixing efficiency at sufficiently large Peclet numbers.
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Affiliation(s)
- Sergey A Vagner
- Institute of Problems of Chemical Physics , Russian Academy of Sciences , 1, Academician Semenov Avenue , Chernogolovka , Moscow , 142432 , Russia
| | - Stanislav A Patlazhan
- Institute of Problems of Chemical Physics , Russian Academy of Sciences , 1, Academician Semenov Avenue , Chernogolovka , Moscow , 142432 , Russia
- Semenov Federal Research Center for Chemical Physics , Russian Academy of Sciences , 4, Kosygin Street , Moscow , 119991 , Russia
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Rotation of Liquid Metal Droplets Solely Driven by the Action of Magnetic Fields. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9071421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The self-rotation of liquid metal droplets (LMDs) has garnered potential for numerous applications, such as chip cooling, fluid mixture, and robotics. However, the controllable self-rotation of LMDs utilizing magnetic fields is still underexplored. Here, we report a novel method to induce self-rotation of LMDs solely utilizing a rotating magnetic field. This is achieved by rotating a pair of permanent magnets around a LMD located at the magnetic field center. The LMD experiences Lorenz force generated by the relative motion between the droplet and the permanent magnets and can be rotated. Remarkably, unlike the actuation induced by electrochemistry, the rotational motion of the droplet induced by magnetic fields avoids the generation of gas bubbles and behaves smoothly and steadily. We investigate the main parameters that affect the self-rotational behaviors of LMDs and validate the theory of this approach. We further demonstrate the ability of accelerating cooling and a mixer enabled by the self-rotation of a LMD. We believe that the presented technique can be conveniently adapted by other systems after necessary modifications and enables new progress in microfluidics, microelectromechanical (MEMS) applications, and micro robotics.
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Flow rate independent gradient generator and application in microfluidic free-flow electrophoresis. Anal Chim Acta 2018; 1044:77-85. [DOI: 10.1016/j.aca.2018.04.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/19/2018] [Accepted: 04/26/2018] [Indexed: 11/19/2022]
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Weijs JH, Bartolo D. Mixing by Unstirring: Hyperuniform Dispersion of Interacting Particles upon Chaotic Advection. PHYSICAL REVIEW LETTERS 2017; 119:048002. [PMID: 29341775 DOI: 10.1103/physrevlett.119.048002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Indexed: 06/07/2023]
Abstract
We show how to achieve both fast and hyperuniform dispersions of particles in viscous fluids. To do so, we first extend the concept of critical random organization to chaotic drives. We show how palindromic sequences of chaotic advection cause microscopic particles to effectively interact at long range, thereby inhibiting critical self-organization. Based on this understanding we go around this limitation and design sequences of stirring and unstirring which simultaneously optimize the speed of particle spreading and the homogeneity of the resulting dispersions.
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Affiliation(s)
- Joost H Weijs
- Univ Lyon, Ens de Lyon, Univ Claude Bernard, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - Denis Bartolo
- Univ Lyon, Ens de Lyon, Univ Claude Bernard, CNRS, Laboratoire de Physique, F-69342 Lyon, France
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Synchronized chaotic targeting and acceleration of surface chemistry in prebiotic hydrothermal microenvironments. Proc Natl Acad Sci U S A 2017; 114:1275-1280. [PMID: 28119504 DOI: 10.1073/pnas.1612924114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Porous mineral formations near subsea alkaline hydrothermal vents embed microenvironments that make them potential hot spots for prebiotic biochemistry. But, synthesis of long-chain macromolecules needed to support higher-order functions in living systems (e.g., polypeptides, proteins, and nucleic acids) cannot occur without enrichment of chemical precursors before initiating polymerization, and identifying a suitable mechanism has become a key unanswered question in the origin of life. Here, we apply simulations and in situ experiments to show how 3D chaotic thermal convection-flows that naturally permeate hydrothermal pore networks-supplies a robust mechanism for focused accumulation at discrete targeted surface sites. This interfacial enrichment is synchronized with bulk homogenization of chemical species, yielding two distinct processes that are seemingly opposed yet synergistically combine to accelerate surface reaction kinetics by several orders of magnitude. Our results suggest that chaotic thermal convection may play a previously unappreciated role in mediating surface-catalyzed synthesis in the prebiotic milieu.
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Xu B, Kuang T, Yu H, Wang M, Turng LS. Enhancement of mixing by different baffle arrays in cavity flows. Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2015.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ober TJ, Foresti D, Lewis JA. Active mixing of complex fluids at the microscale. Proc Natl Acad Sci U S A 2015; 112:12293-8. [PMID: 26396254 PMCID: PMC4603479 DOI: 10.1073/pnas.1509224112] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition.
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Affiliation(s)
- Thomas J Ober
- School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
| | - Daniele Foresti
- School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
| | - Jennifer A Lewis
- School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138
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Deseigne J, Cottin-Bizonne C, Stroock AD, Bocquet L, Ybert C. How a "pinch of salt" can tune chaotic mixing of colloidal suspensions. SOFT MATTER 2014; 10:4795-4799. [PMID: 24909866 DOI: 10.1039/c4sm00455h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Efficient mixing of colloids, particles or molecules is a central issue in many processes. It results from the complex interplay between flow deformations and molecular diffusion, which is generally assumed to control the homogenization processes. In this work we demonstrate on the contrary that despite fixed flow and self-diffusion conditions, the chaotic mixing of colloidal suspensions can be either boosted or inhibited by the sole addition of a trace amount of salt as a co-mixing species. Indeed, this shows that local saline gradients can trigger a chemically driven transport phenomenon, diffusiophoresis, which controls the rate and direction of molecular transport far more efficiently than the usual Brownian diffusion. A simple model combining the elementary ingredients of chaotic mixing with diffusiophoretic transport of the colloids allows rationalization of our observations and highlights how small-scale out-of-equilibrium transport bridges to mixing at much larger scales in a very effective way. Considering chaotic mixing as a prototypal building block for turbulent mixing suggests that these phenomena, occurring whenever the chemical environment is inhomogeneous, might bring interesting perspectives from micro-systems to large-scale situations, with examples ranging from ecosystems to industrial contexts.
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Affiliation(s)
- Julien Deseigne
- Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne, France.
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Bracciale MP, Broggi A, Cerbelli S, Formisano M, Santarelli ML, Scarsella M, Marrocchi A. The impact of chaotic advection on the microstructure of polymer-modified bitumen. AIChE J 2014. [DOI: 10.1002/aic.14361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Maria P. Bracciale
- Dipartimento di Ingegneria Chimica Materiali Ambiente; Sapienza Università di Roma Via Eudossiana 18; 00184 Rome Italy
| | - Alessandra Broggi
- Dipartimento di Ingegneria Chimica Materiali Ambiente; Sapienza Università di Roma Via Eudossiana 18; 00184 Rome Italy
| | - Stefano Cerbelli
- Dipartimento di Ingegneria Chimica Materiali Ambiente; Sapienza Università di Roma Via Eudossiana 18; 00184 Rome Italy
| | - Marco Formisano
- Dipartimento di Ingegneria Chimica Materiali Ambiente; Sapienza Università di Roma Via Eudossiana 18; 00184 Rome Italy
| | - Maria L. Santarelli
- Dipartimento di Ingegneria Chimica Materiali Ambiente; Sapienza Università di Roma Via Eudossiana 18; 00184 Rome Italy
| | - Marco Scarsella
- Dipartimento di Ingegneria Chimica Materiali Ambiente; Sapienza Università di Roma Via Eudossiana 18; 00184 Rome Italy
| | - Assunta Marrocchi
- Dipartimento di Chimica; Università di Perugia; Via Elce di Sotto 8 06123 Perugia Italy
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