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Spatially and temporally resolved measurements of turbulent Rayleigh-Bénard convection by Lagrangian particle tracking of long-lived helium-filled soap bubbles

Bosbach, Johannes and Schanz, Daniel and Godbersen, Philipp and Schröder, Andreas (2021) Spatially and temporally resolved measurements of turbulent Rayleigh-Bénard convection by Lagrangian particle tracking of long-lived helium-filled soap bubbles. In: Proceedings of 14th International Symposium on Particle Image Velocimetry, 1 (1), 1 - 12. ILLINOIS Tech / Paul V. Galvin Library. 14th International Symposium on Particle Image Velocimetry 2021, 01.-04.08.2021, Chicago, USA (online). doi: 10.18409/ispiv.v1i1.208.

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Official URL: https://doi.org/10.18409/ispiv.v1i1.208

Abstract

Rayleigh-Bénard convection (RBC), where a fluid is heated from below and cooled from above, is a prevalent model system to study the fundamentals of thermal convection. Typical for the turbulent RBC system is the occurrence of a large-scale circulation (LSC), which develops by self-organization of thermal plumes, erupted from the thermal boundary layers. In cylindrical samples of aspect ratios close to unity with a high degree of symmetry, the LSC reveals complex short- and long-term dynamics, which has been studied extensively in the past. Direct volumetric measurements of the LSC, however, allowing for a direct insight into the underlying turbulent processes are still rare. To bridge this gap, we performed Lagrangian Particle Tracking (LPT) by using a multi-camera setup, long-lasting, helium-filled soap bubbles and high-power LED arrays. With the "Shake-The-Box" Lagrangian particle tracking algorithm, we were able to instantaneously track up to 560,000 particles in the complete sample volume (~ 1 m³), corresponding to mean inter-particle distances down to 6-8 Kolmogorov lengths. We used the data assimilation scheme ‘FlowFit’, which involves continuity and Navier-Stokesconstraints, to map the scattered velocity and acceleration data on cubic grids, herewith recovering the smallest flow scales. Lagrangian and Eulerian visualizations reveal the dynamics of the large-scale circulation and its interplay with small scale structures, such as thermal plumes and turbulent background fluctuations. As a result, the complex time-dependent behavior of the LSC comprising azimuthal rotations, torsional oscillation and sloshing can be extracted from the data. Further, we found more seldom dynamic events, such as spontaneous reorientations of the LSC in the data from long-term measurements.

Item URL in elib:https://elib.dlr.de/143993/
Document Type:Conference or Workshop Item (Speech)
Additional Information:https://doi.org/10.18409/ispiv.v1i1, https://www.iit.edu/ispiv2021, Paper 188
Title:Spatially and temporally resolved measurements of turbulent Rayleigh-Bénard convection by Lagrangian particle tracking of long-lived helium-filled soap bubbles
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Bosbach, JohannesJohannes.Bosbach (at) dlr.dehttps://orcid.org/0000-0002-1531-127X
Schanz, Danieldaniel.schanz (at) dlr.dehttps://orcid.org/0000-0003-1400-4224
Godbersen, Philippphilipp.godbersen (at) dlr.dehttps://orcid.org/0000-0002-0917-4897
Schröder, Andreasandreas.schroeder (at) dlr.dehttps://orcid.org/0000-0002-6971-9262
Date:August 2021
Journal or Publication Title:Proceedings of 14th International Symposium on Particle Image Velocimetry
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:1
DOI :10.18409/ispiv.v1i1.208
Page Range:1 - 12
Editors:
EditorsEmailEditor's ORCID iD
Christensen, Kenneth T.Kenneth.Christensen@iit.eduUNSPECIFIED
Publisher:ILLINOIS Tech / Paul V. Galvin Library
Series Name:Conference Proceedings
Status:Published
Keywords:Rayleigh-Bénard convection (RBC), large-scale circulation (LSC), high-power LED arrays, "Shake-The-Box", Lagrangian Particle Tracking (LPT), ‘FlowFit’
Event Title:14th International Symposium on Particle Image Velocimetry 2021
Event Location:Chicago, USA (online)
Event Type:international Conference
Event Dates:01.-04.08.2021
Organizer:Illinois Institute of Technology
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Efficient Vehicle
DLR - Research area:Aeronautics
DLR - Program:L EV - Efficient Vehicle
DLR - Research theme (Project):L - Virtual Aircraft and  Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Deposited By: Micknaus, Ilka
Deposited On:06 Jan 2022 17:13
Last Modified:07 Jan 2022 16:18

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