论文标题

涡流的集体运动在旋转湍流对流中引起的逆离心效应

Inverse centrifugal effect induced by collective motion of vortices in rotating turbulent convection

论文作者

Ding, Shan-Shan, Chong, Kai Leong, Shi, Jun-Qiang, Ding, Guang-Yu, Lu, Hao-Yuan, Xia, Ke-Qing, Zhong, Jin-Qiang

论文摘要

当流体系统受到强旋流的影响时,预计离心流体运动,即,较密集(较轻的)流体从(向内)从(向内)向外移动(向内)旋转轴。在这里,我们在实验和数字上都证明了温暖和较轻的涡流在旋转湍流对流中的出乎意料的向外运动。当离心浮力足够强以在涡流场中诱导对称性破裂时,这种异常的涡旋运动发生在快速旋转下,即冷抗气旋的涡度超过了温暖旋风的涡度。我们表明,通过流体动力相互作用,密集的人构的涡旋可以自聚集成连贯的簇,并在这种流动方向上表现出集体运动。有趣的是,群集内涡流速度波动的相关性是无尺度的,相关长度约为群集长度的30%。这种远程相关性导致旋风的集体向外运动。我们的研究提供了对自然界广泛存在的涡流动态的新了解。

When a fluid system is subject to strong rotation, centrifugal fluid motion is expected, i.e., denser (lighter) fluid moves outward (inward) from (toward) the axis of rotation. Here we demonstrate, both experimentally and numerically, the existence of an unexpected outward motion of warm and lighter vortices in rotating turbulent convection. This anomalous vortex motion occurs under rapid rotations when the centrifugal buoyancy is sufficiently strong to induce a symmetry-breaking in the vorticity field, i.e., the vorticity of the cold anticyclones overrides that of the warm cyclones. We show that through hydrodynamic interactions the densely populated vortices can self-aggregate into coherent clusters and exhibit collective motion in this flow regime. Interestingly, the correlation of the vortex velocity fluctuations within a cluster is scale-free, with the correlation length being about 30% of the cluster length. Such long-range correlation leads to the collective outward motion of cyclones. Our study provides new understanding of vortex dynamics that are widely present in nature.

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