Richard J.A.M. Stevens

Physics of Fluids · University of Twente

Publication 116 · Thermal convection

How wide must Rayleigh–Bénard cells be to prevent finite aspect ratio effects in turbulent flow?

R.J.A.M. Stevens, R. Hartmann, R. Verzicco, D. Lohse, J. Fluid Mech. 1000, A58 (2024).

Main finding

Required width is observable specific—about four for selected integrals but up to 16 for variance/local organization here. No universal width or ultimate-regime sufficiency follows.

Heat transport and three Reynolds numbers against cell width at two Rayleigh numbers
How to read the figure. (a) Nusselt number and (b-d) total, vertical and horizontal Reynolds numbers against aspect ratio, for cylindrical and periodic cells at two Rayleigh numbers. These integral quantities reach their wide-domain values by an aspect ratio of about four. Open the full-resolution figure. Figure 1. R.J.A.M. Stevens et al. (2024). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

A box can be wide enough for averages but not fluctuations.

Research context

This is the programme's direct finite-width capstone and links the earlier 2D/wide-domain evidence. The completed claim review now controls CG01, CG04, and limiting/contextual uses in CG09 and CG12; external calibration and downstream use verification remain deferred.

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