Work

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

Year: 2024

Type: article

Abstract: We employ direct numerical simulations to investigate the heat transfer and flow structures in turbulent Rayleigh–Bénard convection in both cylindrical cells and laterally periodic domains, spanning an unprecedentedly wide range of aspect ratios $0.075 \leqslant \varGamma \leqslant 32$ . We focus on Prandtl number ${Pr}=1$ and Rayleigh numbers ${{Ra}}=2\times 10^7$ and ${{Ra}}=10^8$ . In both cases, with increasing aspect ratio, the heat transfer first increases, then reaches a maximum (which is more pronounced for the cylindrical case due to confinement effects), and then slightly goes down again before it finally saturates at the large aspect ratio limit, which is achieved already at $\varGamma \approx 4$ . Already for $\varGamma \gtrsim 0.75$ , the heat transfers in both cylindrical and laterally periodic domains become identical. The large- $\varGamma$ limit for the volume-integrated Reynolds number and the boundary layer thicknesses are also reached at $\varGamma \approx 4$ . However, while the integral flow properties converge at $\varGamma \approx 4$ , the confinement of a cylindrical domain impacts the temperature and velocity variance distributions up to $\varGamma \approx 16$ , as thermal superstructures cannot form close to the sidewall.

Source: Journal of Fluid Mechanics

DOI: 10.1017/jfm.2024.996

Authors: Richard J.A.M. Stevens, Robert Hartmann, Roberto Verzicco, Detlef Lohse

Institutions: Max Planck University of Twente Center for Complex Fluid Dynamics, University of Twente, University of Rome Tor Vergata, Gran Sasso Science Institute, Max Planck Institute for Dynamics and Self-Organization

Language: English

Topic: Fluid Dynamics and Turbulent Flows

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,450

Funder: European Research Council