Richard J.A.M. Stevens

Physics of Fluids · University of Twente

Publication 55 · Thermal convection

Sharp transitions in rotating turbulent convection

K.M.J. Alards, R.P.J. Kunnen, R.J.A.M. Stevens, D. Lohse, F. Toschi, H.J.H. Clercx, Phys. Rev. Fluids 4, 074601 (2019).

Main finding

Two distinct response thresholds appear in the chosen case: heat transport near Ro(c1) ≈ 2.7 and Lagrangian acceleration/plume statistics near Ro(c2) ≈ 2.25. The authors interpret Ro(c2) as mature cyclonic Ekman plumes emerging from the boundary layer and entering the bulk, producing extreme horizontal accelerations.

Root-mean-square Lagrangian accelerations against Rossby number with two critical values marked
How to read the figure. Root-mean-square Lagrangian accelerations, and their ratio, against the Rossby number in rotating turbulent convection, with both critical Rossby numbers marked and insets enlarging the range between them. The acceleration statistics change near Ro = 2.25, distinct from the threshold near Ro = 2.7 at which heat transport responds; that separation is the second critical Rossby number of the title. Figure 2, which plots the Nusselt number, carries only the first threshold. Open the full-resolution figure. Figure 3. K.M.J. Alards et al. (2019). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Heat transfer and Lagrangian plume statistics need not respond at the same rotation threshold, so a single transition marker is insufficient.

Research context

The local Lagrangian statistics separate the heat-transport threshold from a second threshold associated with mature cyclonic Ekman plumes entering the bulk. Both thresholds come from one Rayleigh- and Prandtl-number case and require broader rotating-regime comparison before generalization.

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