Abstract
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, , and at Rayleigh numbers and in a quasi-two-dimensional rectangular cell with unit aspect ratio. By changing the inclination angle of the convection cell, the character of the flow can be changed from moderately turbulent, for , to laminar and steady at . The global heat transfer is found to be insensitive to the drastic reduction of turbulent intensity, with maximal relative variations of the order of at and at , while the Reynolds number, based on the global root-mean-square velocity, is strongly affected with a decay of more than 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.
2 More- Received 5 September 2018
DOI:https://doi.org/10.1103/PhysRevE.99.013108
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