A numerical study is conducted on a natural convection flow in a differentially heated cavity of aspect ratio 4, submitted to a small-extend thermal disturbance localized on the hot wall. The disturbance is a sinusoidally-varying thermal oscillation applied to the hot wall temperature on an area representing of the whole hot wall. The influence of the disturbance location and frequency is investigated with the aim of acting on the flow and consequently maximizing heat transfers. The Rayleigh number is set at and the working fluid is air. Results show that the optimal disturbance location is at the top of the hot wall. The maximal heat transfers are obtained for two disturbance frequencies: the frequency of internal gravity waves and a very low frequency, for which the gain is higher. The disturbance is also responsible for the emergence of travelling waves and the resulting unsteady behavior of the flow is enlightened.

中文翻译：

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遭受小程度热扰动的外壳内自然对流的传热增强：位置和频率的影响


对纵横比为 4 的差热腔中的自然对流进行了数值研究，该腔受到热壁上局部小范围的热扰动。该扰动是施加到代表整个热壁的区域上的热壁温度的正弦变化的热振荡。研究扰动位置和频率的影响，目的是作用于流动，从而使传热最大化。瑞利数设定为 ，工作流体为空气。结果表明，最佳扰动位置位于热墙顶部。最大传热是在两个扰动频率下获得的：内部重力波的频率和增益较高的极低频率。扰动也是行波出现的原因，并且由此产生的流动的不稳定行为也得到了启发。