How surface roughness reduces heat transport for small roughness heights in turbulent Rayleigh–Bénard convection

YZ Zhang, C Sun, Y Bao, Q Zhou - Journal of Fluid Mechanics, 2018 - cambridge.org
Rough surfaces have been widely used as an efficient way to enhance the heat-transfer
efficiency in turbulent thermal convection. In this paper, however, we show that roughness …

Roughness-Facilitated Local Scaling Does Not Imply the Onset of the Ultimate Regime of Thermal Convection

X Zhu, RJAM Stevens, R Verzicco, D Lohse - Physical review letters, 2017 - APS
In thermal convection, roughness is often used as a means to enhance heat transport,
expressed in Nusselt number. Yet there is no consensus on whether the Nusselt vs Rayleigh …

Roughness as a route to the ultimate regime of thermal convection

S Toppaladoddi, S Succi, JS Wettlaufer - Physical review letters, 2017 - APS
We use highly resolved numerical simulations to study turbulent Rayleigh-Bénard
convection in a cell with sinusoidally rough upper and lower surfaces in two dimensions for …

Scaling enabled by multiscale wall roughness in Rayleigh–Bénard turbulence

X Zhu, RJAM Stevens, O Shishkina… - Journal of fluid …, 2019 - cambridge.org
In turbulent Rayleigh–Bénard (RB) convection with regular, mono-scale, surface roughness,
the scaling exponent, when the smaller roughness elements fully protrude through the …

Radiative heating achieves the ultimate regime of thermal convection

S Lepot, S Aumaître, B Gallet - Proceedings of the National …, 2018 - National Acad Sciences
The absorption of light or radiation drives turbulent convection inside stars, supernovae,
frozen lakes, and Earth's mantle. In these contexts, the goal of laboratory and numerical …

Turbulent thermal convection over rough plates with varying roughness geometries

YC **e, KQ **a - Journal of Fluid Mechanics, 2017 - cambridge.org
We present a systematic investigation of the effects of roughness geometry on turbulent
Rayleigh–Bénard convection (RBC) over rough plates with pyramid-shaped and periodically …

The-dependence of the critical roughness height in two-dimensional turbulent Rayleigh–Bénard convection

JL Yang, YZ Zhang, T **, YH Dong… - Journal of Fluid …, 2021 - cambridge.org
The Pr-dependence of the critical roughness height in two-dimensional turbulent Rayleigh–Bénard
convection Page 1 J. Fluid Mech. (2021), vol. 911, A52, doi:10.1017/jfm.2020.1091 The Pr-dependence …

Shear-induced modulation on thermal convection over rough plates

TC **, JZ Wu, YZ Zhang, YL Liu… - Journal of Fluid …, 2022 - cambridge.org
External modulation on thermal convection has been studied extensively to achieve the
control of flow structures and heat-transfer efficiency. In this paper, we carry out direct …

Enhanced heat transfer and reduced flow reversals in turbulent thermal convection with an obstructed centre

YZ Li, X Chen, HD ** - Journal of Fluid Mechanics, 2024 - cambridge.org
We report an experimental study about the effect of an obstructed centre on heat transport
and flow reversal by inserting an adiabatic cylinder at the centre of a quasi-two-dimensional …

Wall roughness induces asymptotic ultimate turbulence

X Zhu, RA Verschoof, D Bakhuis, SG Huisman… - Nature physics, 2018 - nature.com
Turbulence governs the transport of heat, mass and momentum on multiple scales. In real-
world applications, wall-bounded turbulence typically involves surfaces that are rough; …