1
|
García-Fernández L, Bataller H, Fruton P, Giraudet C, Vailati A, Croccolo F. Stabilized convection in a ternary mixture with two Soret coefficients of opposite sign. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:52. [PMID: 35633426 PMCID: PMC9148296 DOI: 10.1140/epje/s10189-022-00202-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
We performed ground-based experiments on the sample polystyrene-toluene-cyclohexane in order to complement the experimental activities in microgravity conditions related to the ESA projects DCMIX4 and Giant Fluctuations. After applying a stabilizing thermal gradient by heating from above a layer of the fluid mixture, we studied over many hours the density variations in the bidimensional horizontal field by means of a Shadowgraph optical setup. The resulting images evidence the appearance of convective instability after a diffusive time associated with the binary molecular solvent consisting of toluene and cyclohexane, confirming the negative sign of the Soret coefficient of this mixture. After a larger diffusive time related to mass diffusion of the polystyrene in the binary solvent, convection was suppressed by the increasing stabilizing density gradient originated by the Soret-induced concentration gradient of the polymer. This is compatible with a positive sign of the Soret coefficient of the polymer in the binary solvent.
Collapse
Affiliation(s)
- Loreto García-Fernández
- E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Universite de Pau et des Pays de l’Adour, Anglet, France
- Centre National d’Études Spatiales (CNES), 2, Place Maurice Quentin, Paris, France
- Department of Structure of Matter, Thermal Physics and Electronics, Faculty of Physics, University Complutense of Madrid, Madrid, Spain
| | - Henri Bataller
- E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Universite de Pau et des Pays de l’Adour, Anglet, France
| | - Paul Fruton
- E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Universite de Pau et des Pays de l’Adour, Anglet, France
| | - Cédric Giraudet
- E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Universite de Pau et des Pays de l’Adour, Anglet, France
| | - Alberto Vailati
- Dipartimento di Fisica “A. Pontremoli”, Università degli Studi di Milano, Milan, Italy
| | - Fabrizio Croccolo
- E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Universite de Pau et des Pays de l’Adour, Anglet, France
| |
Collapse
|
2
|
Alonso A, Mercader I, Batiste O. Time-dependent patterns in quasivertical cylindrical binary convection. Phys Rev E 2018; 97:023108. [PMID: 29548138 DOI: 10.1103/physreve.97.023108] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Indexed: 11/07/2022]
Abstract
This paper reports on numerical investigations of the effect of a slight inclination α on pattern formation in a shallow vertical cylindrical cell heated from below for binary mixtures with a positive value of the Soret coefficient. By using direct numerical simulation of the three-dimensional Boussinesq equations with Soret effect in cylindrical geometry, we show that a slight inclination of the cell in the range α≈0.036rad=2^{∘} strongly influences pattern selection. The large-scale shear flow (LSSF) induced by the small tilt of gravity overcomes the squarelike arrangements observed in noninclined cylinders in the Soret regime, stratifies the fluid along the direction of inclination, and produces an enhanced separation of the two components of the mixture. The competition between shear effects and horizontal and vertical buoyancy alters significantly the dynamics observed in noninclined convection. Additional unexpected time-dependent patterns coexist with the basic LSSF. We focus on an unsual periodic state recently discovered in an experiment, the so-called superhighway convection state (SHC), in which ascending and descending regions of fluid move in opposite directions. We provide numerical confirmation that Boussinesq Navier-Stokes equations with standard boundary conditions contain the essential ingredients that allow for the existence of such a state. Also, we obtain a persistent heteroclinic structure where regular oscillations between a SHC pattern and a state of nearly stationary longitudinal rolls take place. We characterize numerically these time-dependent patterns and investigate the dynamics around the threshold of convection.
Collapse
Affiliation(s)
- Arantxa Alonso
- Departament de Física, Universitat Politècnica de Catalunya, Mòdul B4, 08034 Barcelona, Spain
| | - Isabel Mercader
- Departament de Física, Universitat Politècnica de Catalunya, Mòdul B4, 08034 Barcelona, Spain
| | - Oriol Batiste
- Departament de Física, Universitat Politècnica de Catalunya, Mòdul B4, 08034 Barcelona, Spain
| |
Collapse
|
3
|
Italia M, Croccolo F, Scheffold F, Vailati A. Inclined layer convection in a colloidal suspension with negative Soret coefficient at large solutal Rayleigh numbers. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:101. [PMID: 25348665 DOI: 10.1140/epje/i2014-14101-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 10/02/2014] [Accepted: 10/08/2014] [Indexed: 06/04/2023]
Abstract
Convection in an inclined layer of fluid is affected by the presence of a component of the acceleration of gravity perpendicular to the density gradient that drives the convective motion. In this work we investigate the solutal convection of a colloidal suspension characterized by a negative Soret coefficient. Convection is induced by heating the suspension from above, and at large solutal Rayleigh numbers (of the order of 10(7)-10(8)) convective spoke patterns form. We show that in the presence of a marginal inclination of the cell as small as 19 mrad the isotropy of the spoke pattern is broken and the convective patterns tend to align in the direction of the inclination. At intermediate inclinations of the order of 33 mrad ordered square patterns are obtained, while at inclination of the order of 67 mrad the strong shear flow determined by the inclination gives rise to ascending and descending sheets of fluid aligned parallel to the direction of inclination.
Collapse
Affiliation(s)
- Matteo Italia
- Dipartimento di Fisica, Università degli Studi di Milano, I-20133, Milano, Italy
| | | | | | | |
Collapse
|
4
|
Croccolo F, Scheffold F, Vailati A. Effect of a marginal inclination on pattern formation in a binary liquid mixture under thermal stress. PHYSICAL REVIEW LETTERS 2013; 111:014502. [PMID: 23863004 DOI: 10.1103/physrevlett.111.014502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Indexed: 06/02/2023]
Abstract
Convective motions in a fluid layer are affected by its orientation with respect to the gravitational field. We investigate the long-term stability of a thermally stressed layer of a binary liquid mixture and show that pattern formation is strongly affected by marginal inclinations as small as a few milliradians. At small Rayleigh numbers, the mass transfer is dominated by the induced large scale shear flow, while at larger Rayleigh numbers, it is dominated by solutal convection. At the transition, the balance between the solutal and shear flows gives rise to drifting columnar flows moving in opposite directions along parallel lanes in a superhighway configuration.
Collapse
Affiliation(s)
- Fabrizio Croccolo
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland.
| | | | | |
Collapse
|
5
|
Pal P, Kumar K, Maity P, Dana SK. Pattern dynamics near inverse homoclinic bifurcation in fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:023001. [PMID: 23496604 DOI: 10.1103/physreve.87.023001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Indexed: 06/01/2023]
Abstract
We report the pattern dynamics in the vicinity of an inverse homoclinic bifurcation in an extended dissipative system. We observe, in direct numerical simulations of three dimensional Rayleigh-Bénard convection with stress-free top and bottom plates, a spontaneous breaking of a competition of two mutually perpendicular sets of oscillating cross rolls to one of two possible sets of oscillating cross rolls as the Rayleigh number is raised above a critical value. The time period of the oscillating cross-roll patterns diverges and shows scaling behavior near the bifurcation point. This is an example of a transition from nonlocal to local pattern dynamics near an inverse homoclinic bifurcation. We also present a simple four-mode model that captures the pattern dynamics quite well.
Collapse
Affiliation(s)
- Pinaki Pal
- Department of Mathematics, National Institute of Technology, Durgapur-713 209, India
| | | | | | | |
Collapse
|