Transitions in turbulent rotating convection: A Lagrangian perspective

Rajaei, Hadi; Joshi, Pranav; Alards, Kmj Kim; Kunnen, Rudie; Toschi, Federico; Clercx, Hjh Herman

doi:10.1103/physreve.93.043129

Cited by 19 publications

(63 citation statements)

References 38 publications

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“…First, we introduce the Rayleigh-Bénard setup, that is described in detail in [13,23]. The setup includes a convection cell and an optical tracking system, both mounted on a rotating table.…”

Section: A Rayleigh-bénard Convectionmentioning

confidence: 99%

“…In the experiments we cannot treat the boundary layer (BL) separately, however we realize that the number of measurement points inside the BL is minimal due to particles being slightly heavier than the fluid and due to an offset of about 1 mm between the plate and the field of view of the cameras. In terms of the viscous boundary layer thickness δ u , that is determined as the position of the maximum horizontal rms velocity as in [13], this corresponds to 0.167δ u for Ek = ∞ and 0.617δ u for Ek = 7.2 · 10 −6 . As a result, we can assume that the statistics measured experimentally in the top measurement volume, behave as if we are excluding the BL (as in the light-green volume in figure 1).…”

Section: A Rayleigh-bénard Convectionmentioning

confidence: 99%

“…The boundary layer is a special region of the flow, where the typical statistical characteristics of bulk turbulence are not applicable anymore [26,27]. In RBC, the boundary layer dynamics is significantly influenced by rotation [13,14] and moreover plays an important role in the transition to the enhanced heat flux state, mentioned before [8,15]. More precisely, a transition is observed from a Prandtl-Blasius boundary layer for lower rotation rates, to an Ekman boundary layer for higher rotation rates [13].…”

Section: Introductionmentioning

confidence: 99%

“…In RBC the flow is buoyancy driven: a fluid is heated from below and cooled from above. Rotating a RBC system around its vertical axis induces sharp transitions in the heat flux and boundary layer dynamics and a significant change of the dominant coherent flow structures [8,[13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…In RBC, the boundary layer dynamics is significantly influenced by rotation [13,14] and moreover plays an important role in the transition to the enhanced heat flux state, mentioned before [8,15]. More precisely, a transition is observed from a Prandtl-Blasius boundary layer for lower rotation rates, to an Ekman boundary layer for higher rotation rates [13]. A significant difference between these two types of boundary layers is that the Prandtl-Blasius boundary layer is passive and does not interact with the bulk, while the Ekman boundary layer dynamics is actively driven by the bulk flow.…”

Section: Introductionmentioning

confidence: 99%

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Geometry of tracer trajectories in rotating turbulent flows

et al. 2017

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The geometry of passive tracer trajectories is studied in two different types of rotating turbulent flows; rotating Rayleigh-Bénard convection (RBC; experiments and direct numerical simulations) and rotating electromagnetically forced turbulence (EFT; experiments). This geometry is fully described by the curvature and torsion of trajectories and from these geometrical quantities we can subtract information on the typical flow structures at different rotation rates. Previous studies, focusing on non-rotating homogeneous isotropic turbulence (HIT), show that the probability density functions (PDFs) of curvature and torsion reveal pronounced power laws. However, the set-ups studied here involve inhomogeneous turbulence and in RBC the flow near the horizontal plates is definitely anisotropic. We want to investigate how the typical shapes of the curvature and torsion PDFs, including the pronounced scaling laws, are influenced by this level of anisotropy and inhomogeneity and how this effect changes with rotation. A first effect of rotation is observed as a shift of the curvature and torsion PDFs towards higher values in the case of RBC and towards lower values in the case of EFT. This shift is related to the length scale of typical vortical structures that decreases with rotation in RBC, but increases with rotation in EFT, explaining the opposite shifts of the curvature (and torsion) PDFs. A second remarkable observation is that in RBC the HIT scaling laws are always recovered, as long as the boundary layer (BL) is excluded. This suggests that these scaling laws are very robust and hold as long as we measure in the turbulent bulk. In the BL of the RBC cell, however, the scaling deviates from the HIT prediction for lower rotation rates. This scaling behavior is found to be consistent with the coupling between the boundary layer dynamics and the bulk flow, that changes under rotation. In particular, it is found that the active coupling of the Ekman-type boundary layer with the bulk flow suppresses anisotropy in the BL region for increasing rotation rates.

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Section: A Rayleigh-bénard Convectionmentioning

confidence: 99%

Section: A Rayleigh-bénard Convectionmentioning

confidence: 99%