Richard J.A.M. Stevens

Physics of Fluids · University of Twente

Publication 18 · Thermal convection

Thermal boundary layer profiles in turbulent Rayleigh-Bénard convection in a cylindrical sample

R.J.A.M. Stevens, Q. Zhou, S. Grossmann, R. Verzicco, K.-Q Xia, D. Lohse, Phys. Rev. E 85, 027301 (2012).

Main finding

Dynamic rescaling is a useful conditional diagnostic of thickness variability and produces closer PB-like centre-axis means. It does not by itself validate laminar Pohlhausen physics, establish full resolution, or identify the residual's cause.

Thermal boundary layer profiles against unrescaled and dynamically rescaled wall coordinates
How to read the figure. Thermal boundary layer profiles plotted against the wall coordinate as measured (a) and after dynamic rescaling by the instantaneous thickness (b), with the shape factor against Rayleigh number inset. Rescaling collapses the profiles closer to the laminar Pohlhausen curve: a moving coordinate reveals structure that fixed-coordinate averaging smears out. The closer agreement is a diagnostic of thickness variability, not a validation of laminar Pohlhausen physics nor evidence that the simulation is fully resolved. Open the full-resolution figure. Figure 2. R.J.A.M. Stevens et al. (2012). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

A moving coordinate can reveal structure hidden by averaging.

Research context

Prandtl-Blasius temperature and velocity boundary layer profiles in turbulent… and Horizontal structures of velocity and temperature boundary layers in… establish the dynamic-rescaling method in quasi-two-dimensional data and already show its normalization, shape-factor, dimensionality, selection, and causal limits. Radial boundary layer structure and Nusselt number in Rayleigh-Bénard…, Prandtl and Rayleigh number dependence of heat transport in…, and Effect of plumes on measuring the large scale circulation… supply the reused three-dimensional simulations; only Radial boundary layer structure and Nusselt number in Rayleigh-Bénard… currently has a detailed baseline. That paper also shows radial and numerical-fidelity dependence in the same code family. Logarithmic temperature profiles in turbulent Rayleigh-Bénard convection finds log-compatible bulk profiles near the sidewall at different vertical ranges and regime coverage.

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