Richard J.A.M. Stevens

Professor at the University of Twente

Wind energy · Turbulence · Environmental flows

Publication 54 · Thermal convection

Turbulent thermal superstructures in Rayleigh-Bénard convection

R.J.A.M. Stevens, A. Blass, X. Zhu, R. Verzicco, D. Lohse, Phys. Rev. Fluids 3, 041501(R) (2018).

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Main finding

Thermal superstructures persist through Ra=10^9 in the sampled Pr=1 simulations; no weakening with Ra is found over this finite range. Approximate large-domain thresholds reported are Γ≈4 for Nu and volume Reynolds number, 8 for horizontally averaged higher moments and temperature–vertical-velocity correlation, 32 for integral scales, and 64 for spectral peak locations.

Integral scales, heat transport and moments against aspect ratio for three Rayleigh numbers
How to read the figure. Integral scales, Nusselt number, higher moments and Reynolds number ratios against the horizontal aspect ratio of the domain, at three Rayleigh numbers. The thermal superstructures do not weaken as the Rayleigh number rises across this range. Different quantities need different domain widths before they stop changing: about four aspect ratios for the Nusselt number, thirty-two for the integral scales, sixty-four for the spectral peaks. Open the full-resolution figure. Figure 4. R.J.A.M. Stevens et al. (2018). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Turbulence can retain large-scale order, but the inferred structure scale depends on the diagnostic and domain width.

Research context

A later reanalysis (read the finding) adds lower-Rayleigh-number cases, separates temperature and velocity coherence scales, and corrects the spectral analysis. Related wall-sheared convection (read the finding) examines how imposed shear reorganizes these large structures.

Related findings: Coherence of temperature and velocity superstructures in turbulent Rayleigh-Bénard flow; How wide must Rayleigh–Bénard cells be to prevent finite aspect ratio effects in turbulent flow?.

View in the complete publication list Related thermal convection research