Recent studies of rotating Rayleigh–B'enard convection at high rotation rates and strong thermal forcing have shown a significant discrepancy in total heat transport between experiments on a confined cylindrical domain on the one hand and simulations on a laterally unconfined periodic domain on the other. This paper addresses this discrepancy using direct numerical simulations on a cylindrical domain. An analysis of the flow field reveals a region of enhanced convection near the wall, the sidewall circulation. The sidewall circulation rotates slowly within the cylinder in anticyclonic direction. It has a convoluted structure, illustrated by mean flow fields in horizontal cross-sections of the flow where instantaneous snapshots are compensated for the orientation of the sidewall circulation before averaging. Through separate analysis of the sidewall region and the inner bulk flow, we find that for higher values of the thermal forcing the heat transport in the inner part of the cylindrical domain, outside the sidewall circulation region, coincides with the heat transport on the unconfined periodic domain. Thus the sidewall circulation accounts for the differences in heat transfer between the two considered domains, while in the bulk the turbulent heat flux is the same as that of a laterally unbounded periodic domain. Therefore, experiments, with their inherent confinement, can still provide turbulence akin to the unbounded domains of simulations, and at more extreme values of the governing parameters for thermal forcing and rotation. We also provide experimental evidence for the existence of the sidewall circulation that is in close agreement with the simulation results.

中文翻译：

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局限在细长圆柱体中的湍流旋转对流：侧壁循环

最近在高转速下旋转瑞利-贝纳德对流和强大的热强迫的研究表明，一方面在密闭圆柱域上进行的实验与另一方面在横向无侧限周期域上的模拟之间，总传热存在显着差异。本文使用圆柱域上的直接数值模拟解决了这一差异。对流场的分析显示出靠近壁的对流区域，即侧壁循环。侧壁循环在圆柱体内沿反气旋方向缓慢旋转。它具有回旋结构，通过在水平横截面上的平均流场进行说明，其中在平均之前对瞬时快照补偿了侧壁循环的方向。通过对侧壁区域和内部整体流动的单独分析，我们发现，对于较高的热强迫值，在侧壁循环区域之外的圆柱域内部的热传递与无约束周期上的热传递一致域。因此，侧壁循环解释了两个所考虑的区域之间的传热差异，而总体而言，湍流的热通量与横向无边界的周期性区域的湍流热通量相同。因此，实验由于其固有的局限性，仍可以提供类似于模拟的无限域的湍流，并且可以为热强迫和旋转提供更极端的控制参数值。