Heat transport enhancement in confined Rayleigh-Bénard convection feels the shape of the container ^(a)

Abstract Moderate spatial confinement enhances the heat transfer in turbulent Rayleigh-Bénard (RB) convection (Chong K. L. et al. , Phys. Rev. Lett ., 115 (2015) 264503). Here, by performing direct numerical simulations, we answer question how shape of RB cell affects this enhancement. We compare three different geometries: a box with rectangular base ( i.e. stronger confined one horizontal direction), square equally both directions), and cylinder symmetrically radial direction). In all cases can be described same parameter given as height-over-width aspect ratio. The explored range is $1\le\Gamma^{-1}\le64$ $10^7\le\mathrm{Ra}\le 10^{10}$ for Rayleigh number, Prandtl number $\mathrm{Pr}=4.38$ . find that optimal $\Gamma^{-1}_\mathrm{opt}$ maximal actual enhancement strongly depend on geometry. differences explained formation vertically coherent flow structures within specific geometries. largest cylindrical cell, owing to domain-spanning structure at