Large-scale turbulent structures in liquid metal Rayleigh Bénard convection experiment*

We present experimental results conducted on a 1 meter by 1 meter Rayleigh-Bénard experiment with large aspect ratio length to height Γ = 25.

We conducted experiments in the same setup with two liquids at moderate and very low Prandtl numbers Pr: water (Pr ≈ 6) and the eutectic metal alloy GaInSn (Pr ≈ 0.03). We explore Rayleigh numbers Ra ranging from 10⁵ to 10⁷.

Our study focuses on characterizing the self-organized large scale structures that emerges from the turbulent convective flow. In particular, we will show how the structure length-scale varies with Ra and Pr, and compare our results with numerical simulations at low and high Pr (Pandey et al. 2018, Stevens et al. 2018, Vieweg et al. 2020), as well as a similar experiment conducted with water (Moller et al. 2020, Kaufer et al. 2023). We will also connect the observed flow dynamics back to experiments and numerics at low Pr for smaller aspect ratios Γ = 2, 3 and 5 (Vogt et al. 2018, Teimurazov et al. 2023) to gain further insights on the heat transport and flow organization.