发表机构
University of Science and Technology of China（中国科学技术大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过实空间能量级联的球几何分解湍流局地能量传递，结合直接数值模拟揭示其与流体微元变形动力学的纯力学联系，明确了应变自放大与涡旋拉伸的作用及级联边界。
AI 中文摘要
湍流中跨尺度的局地能量传递如何编码在流体微元的瞬时变形中，仍是一个基础问题。我们利用长度尺度ℓ处实空间能量级联的球几何，通过严格推导表明，该能量传递可通过应变自放大和涡旋拉伸进行局部分解，其系数等于球形流体邻域的比转动惯量2/5(ℓ/2)²。直接数值模拟显示，该贡献捕获了主导的局地能量传递，并定义了分隔正向与反向级联事件的统计边界。进一步的纵向与横向分解表明，支撑Kolmogorov 4/5定律的纵向传递仅由应变自放大控制，而涡旋拉伸则通过横向分量介入。这些结果确立了湍流能量级联与流体微元局地旋转及变形动力学之间的纯力学联系。
英文摘要
How the local energy transfer across scales in turbulence is encoded in the instantaneous deformation of fluid elements remains a fundamental question. We exploit the spherical geometry of the real-space energy cascade at length scale $\ell$. An exact derivation shows that it can be decomposed locally by strain self-amplification and vortex stretching, with a coefficient equal to the specific moment of inertia $2/5(\ell/2)^2$ of a spherical fluid neighborhood. Direct numerical simulations show that this contribution captures the dominant local transfer and defines a statistical boundary separating forward- and inverse-cascade events. A further longitudinal and transverse decomposition reveals that the longitudinal transfer underlying Kolmogorov's $4/5$ law is governed solely by strain self-amplification, whereas vortex stretching enters through the transverse component. These results establish a purely mechanical connection between turbulent energy cascade and the local rotational and deformational dynamics of fluid elements.
