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Study on Dynamics of Large-Scale Circulation in Single-Layer FC77 RBC Experimental Setup

This study examines the properties and behaviors of the azimuthal temperature profile in a single-layer FC77 Rayleigh–Bénard convection experimental setup. The cessation frequency, statistics of amplitude and angle, flow modes, oscillations, and power spectra are analyzed using Multi-thermal Probe, TEE, and SF methods. The influence of Prandtl number on the Large-Scale Circulation is explored, along with variations in flow modes and motions during cessation. Insights on sloshing, twisting motions, and power spectra provide a comprehensive understanding of the system dynamics. Analysis based on cited research by Q. Zhou, H.-D. Xi, S.-Q. Zhou, C. Sun, K.-Q. Xia (JFM, 2009) and E. Brown, G. Ahlers (JFM, 2006).

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Study on Dynamics of Large-Scale Circulation in Single-Layer FC77 RBC Experimental Setup

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  1. Dynamics of LSC insingle layer FC77 RBC

  2. Experimental setup D 3 4 2 5 1 6 8 7 N H=D 1 E 5 Inner Diameter D=2.5mm Outer Diameter D=10mm 6 8 7 Level condition: E:0.0015 rad N:0.002 rad 20mm 0.7mm

  3. Measurement Condition • Pr=19.4(T_center=40oC) • Ra=2.0*1011 • Aspect ratio=1 • Measurement period:29.05days (940774 run) • Method used: Multi-thermal probe method Analysis: TEE (Temperature Extreme Extraction) SF (Sinusoidal Fitting)

  4. TEE and SF methods Q. Zhou, H.-D. Xi, S.-Q. Zhou C. Sun and K.-Q. Xia JFM 2009

  5. Top

  6. Middle

  7. Bottom

  8. Properties of the azimuthal temperature profile 3 4 2 NORTH 1 EAST 5 6 8 7

  9. Cessation Frequency • Using the same criteria as Xi HD used, the cessation frequency of different layer is: A_threshold=0.3*<A>

  10. HD Xi &KQ XIA 2006 PRE,73,056312 The cessation frequency is almost the same as that of single layer water RBC(the same aspect ratio). Thus the influence of Pr number on LSC is not strong. E.Brown &G. Ahlers, JFM,2006,568,pp351-386

  11. Statistics of A and ϴ using the SF method

  12. Statistical analysis of A and ϴ

  13. Statistical analysis of A and ϴ

  14. Statistical analysis of A and ϴ

  15. Statistical analysis of A and ϴ

  16. Statistical analysis of A and ϴ

  17. Statistical analysis of A and ϴ

  18. Different Flow mode

  19. Different Flow Mode Cessation  simultaneously 

  20. Different Flow Mode Reversal without cessation

  21. Different Flow Mode SRM-DRM-SRM transition

  22. Different Flow Mode From top to below: Phase during a cessation Amplitude during a cessation Complex flow mode during cessation Simultaneous cessation part (About 2 times the plume turn over time)

  23. Twisting and sloshing motion of the Large-scale circulation

  24. HD Xi PRL 2009 E.Brown JFM 2009

  25. Sloshing and Twisting oscillation of the Large-scale circulation The motion of LSC in one cycle. t=0 t=1/4T t=1/2T t=3/4T

  26. Power spectrum of ϴ

  27. Coherent power spectrum of ϴ(Top and bottom)

  28. Power spectrum of temperature measured inside the sidewall(Top)

  29. Power spectrum of temperature measured inside the sidewall(Middle)

  30. Power spectrum of temperature measured inside the sidewall(Bottom)

  31. Example of sloshing motion

  32. Power spectrum of off-center distance

  33. Cross correlation of off-center distance

  34. PDF of off-center distance

  35. Thanks!

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