2018/09/04 by Linfeng Jiang, Chao Sun, Enrico Calzavarini · 24 citations
Engineering · Physics and Astronomy · #Combustion and flame dynamics #Convection #Convective heat transfer #Fluid Dynamics and Turbulent Flows #Heat Transfer Mechanisms #Heat flux #Heat transfer #Laminar flow #Mechanics #Natural convection #Nusselt number #Physics #Prandtl number #Rayleigh number #Reynolds number #Thermodynamics #Turbulence #Turbulent Prandtl number #physics.flu-dyn
paper · pdf · doi:10.1103/physreve.99.013108
published in Physical review. E 99(1), 013108 (American Physical Society) · 11 pages, 9 figures (figure 2 here in low resolution)
arxiv created 2018/09/04 · openalex publication_date 2019/01/22 · arxiv updated 2019/01/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the dependency of the magnitude of heat transfer in a convection cell as a function of its inclination by means of experiments and simulations. The study is performed with a working fluid of large Prandtl number, Pr\ensuremath≃480, and at Rayleigh numbers Ra\ensuremath≃108 and Ra\ensuremath≃5\ifmmode×\else\texttimes\fi108 in a quasi-two-dimensional rectangular cell with unit aspect ratio. By changing the inclination angle (\ensuremathβ) of the convection cell, the character of the flow can be changed from moderately turbulent, for \ensuremathβ=0^\ensuremath∘, to laminar and steady at \ensuremathβ=90^\ensuremath∘. The global heat transfer is found to be insensitive to the drastic reduction of turbulent intensity, with maximal relative variations of the order of 20% at Ra\ensuremath≃108 and 10% at Ra\ensuremath≃5\ifmmode×\else\texttimes\fi108, while the Reynolds number, based on the global root-mean-square velocity, is strongly affected with a decay of more than 85% occurring in the laminar regime. We show that the intensity of the heat flux in the turbulent regime can be only weakly enhanced by establishing a large-scale circulation flow by means of small inclinations. However, in the laminar regime the heat is transported solely by a slow large-scale circulation flow which exhibits large correlations between the velocity and temperature fields. For inclination angles close to the transition regime in-between the turbulentlike and laminar state, a quasiperiodic heat-flow bursting phenomenon is observed.