Heat transport in natural convection commonly encountered in natural and engineering flows is affected by buoyancy forces and shear. The effect of rotational shear on heat transport is examined here. Direct numerical simulation of Rayleigh-Bénard convection (RBC) with a rotating lid is performed at various rotation Reynolds numbers (Re) and Rayleigh numbers (Ra). The simulations are done for a range $\text{Ra}\in [2\times {10}^3,2\times {10}^7]$ and $\text{Re}\in [300,3000]$. The rotating lid induces a shear into the flow resulting in two prominent flow regimes: a rotation-dominated (RD) regime and a convection-dominated (CD) regime. The RD and CD regimes are identified based on the heat transport scaling exponent of Ra. The flow topology in these two regimes is distinct, with the CD flow showing more RBC-like flow structures while the RD regime shows a central axial vortex flow. The variations of boundary layer thickness with Ra and Re also demonstrate the regimes. A parameter $\chi \left(\text{Ra,Re}\right)$ is developed to demarcate the two regimes.

中文翻译：

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自然对流中的热传递定标，旋转导致剪切

在自然和工程流中通常遇到的自然对流中的热传递受浮力和剪切力的影响。在此检查旋转剪切对传热的影响。在不同的旋转雷诺数（Re）和瑞利数（Ra）下，对带有旋转盖的瑞利-贝纳德对流（RBC）进行直接数值模拟。在一定范围内进行仿真$\text{镭}\in [2\times {10}^3，2\times {10}^7]$ 和 $\text{回覆}\in [300，3000]$。旋转的盖子在流动中引起剪切，从而产生两个突出的流动状态：以旋转为主的（RD）状态和以对流为主的（CD）状态。根据Ra的热传递定标指数确定RD和CD方案。这两种情况下的流动拓扑是截然不同的，其中CD流动显示出更多的RBC样流动结构，而RD则显示出中心轴向涡流。边界层厚度随Ra和Re的变化也证明了这种状态。一个参数$\chi （\text{罕见}）$ 旨在划分这两种政权。