Effect of domain aspect ratio on the velocity-temperature correlation in Rayleigh-Benard Convection
ORAL
Abstract
In Rayleigh-Bénard convection, the turbulent convective heat flux 〈wθ〉 is a key contributor to the Nusselt number (Nu), yet the scale-by-scale dynamics governing its evolution, particularly under varying domain geometries, require further clarification. This study investigates the spectral budget of 〈wθ〉 across a range of aspect ratios (Γ) to elucidate how production, transport, and dissipation mechanisms vary with Γ across spatial scales and wall-normal positions. Direct numerical simulations of planar Rayleigh-Bénard convection are conducted at three Rayleigh numbers (Ra = 105, 6 × 106, and 4 × 108), each computed for three aspect ratios: Γ = 5π/16 (small), 5π/4 (medium), and 5π (large). Our results reveal that large-scale thermal structures dominate the production and redistribution terms in the 〈wθ〉 budget, particularly in large-Γ domains. However, these structures remain confined to the bulk region while small-sclae thermal structures govern heat transport in the near-wall regions. Consequently, even in wider domains, the contribution of large-scale structures to Nu scaling stays limited, revealing a fundamental separation between bulk and boundary-layer dynamics.
*This work was performed in part during the Fifth Madrid Summer Workshop, funded by the European Research Council under the Caust grant ERC-AdG-101018287. This research used resources of the Argonne Leadership Computing Facility, a U.S. Department of Energy (DOE) Office of Science user facility at Argonne National Laboratory, and is based on research supported by the U.S. DOE Office of Science-Advanced Scientific Computing Research Program, under Contract No. DE-AC02-06CH11357. The authors acknowledge the use of the Carya cluster and are grateful to Dr. J. Ebalunode of the University of Houston Research Computing Data Core for his support.
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Presenters
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Sara Bedolla
- University of Houston