Probing turbulent superstructures in Rayleigh-Bénard convection by Lagrangian trajectory clusters

Research output: Journal contributionsJournal articlesResearchpeer-review

Authors

We analyze large-scale patterns in three-dimensional turbulent convection in a horizontally extended square convection cell by Lagrangian particle trajectories calculated in direct numerical simulations. A simulation run at a Prandtl number Pr =0.7, a Rayleigh number Ra =105, and an aspect ratio Γ=16 is therefore considered. These large-scale structures, which are denoted as turbulent superstructures of convection, are detected by the spectrum of the graph Laplacian matrix. Our investigation, which follows Hadjighasem et al. [Phys. Rev. E 93, 063107 (2016)2470-004510.1103/PhysRevE.93.063107], builds a weighted and undirected graph from the trajectory points of Lagrangian particles. Weights at the edges of the graph are determined by a mean dynamical distance between different particle trajectories. It is demonstrated that the resulting trajectory clusters, which are obtained by a subsequent k-means clustering, coincide with the superstructures in the Eulerian frame of reference. Furthermore, the characteristic times τL and lengths λUL of the superstructures in the Lagrangian frame of reference agree very well with their Eulerian counterparts, τ and λU, respectively. This trajectory-based clustering is found to work for times tτ≈τL. Longer time periods tτL require a change of the analysis method to a density-based trajectory clustering by means of time-averaged Lagrangian pseudotrajectories, which is applied in this context for the first time. A small coherent subset of the pseudotrajectories is obtained in this way consisting of those Lagrangian particles that are trapped for long times in the core of the superstructure circulation rolls and are thus not subject to ongoing turbulent dispersion.

Original languageEnglish
Article number113502
JournalPhysical Review Fluids
Volume3
Issue number11
ISSN2469-990X
DOIs
Publication statusPublished - 15.11.2018

Recently viewed

Researchers

  1. Stefan Baumgärtner

Publications

  1. Using authentic representations of practice in teacher education
  2. Wie partizipativ sind Bottom-up-Transformationen?
  3. A Configurational Approach to Investigating the Relationship Between Organizational Culture and Organizational Effectiveness Using Fuzzy-Set Analysis
  4. Beyond Urban Challenges-Virtual Reality Tools in Participatory Design Processes
  5. Ästhetikkolumne
  6. Where do the data live?
  7. Work availability types and well-being in Germany–a latent class analysis among a nationally representative sample
  8. Log in and breathe out: cost-effectiveness of internet-based recreation training for better sleep in stressed employees
  9. Governmental activity, integration, and agglomeration
  10. Validation of an online imitation-inhibition task
  11. Credit constraints, endogenous innovations, and price setting in international trade
  12. art thinking doing art: Artistic Practices in Educational Contexts from 1900 to Today
  13. Problemlösen in der Sekundarstufe I
  14. Students’ perceptions of and conclusions from their first assessment experience at university
  15. Substance Flows Associated with Medical Care - Significance of Different Sources
  16. Reconstructing the “biopiracy” debate from a justice perspective
  17. Leverage points for addressing marine and coastal pollution
  18. The global context and people at work: Special issue introduction
  19. Human-Value-Oriented Digital Social Innovation: A Multilevel Design Framework
  20. Systematic distributions of interaction strengths across tree interaction networks yield positive diversity–productivity relationships
  21. Hydrological tracers for assessing transport and dissipation processes of pesticides in a model constructed wetland system
  22. Use of Chemotaxonomy To Study the Influence of Benzalkonium Chloride on Bacterial Populations in Biodegradation Testing
  23. Balanced Scorecard implementations – The case of a city hall
  24. Different sizes, similar challenges
  25. Benno Reifenberg (1892-1970)
  26. Networked Disruption
  27. Commitment Strategies for Sustainability
  28. Is There a Way Back or Can the Internet Remember its Own History?
  29. Development perspectives for the application of autonomous, unmanned aerial systems (UASs) in wildlife conservation
  30. Study on AZ31 magnesium alloy-based surface composite through friction stir processing