湍流中高斯子系综的拉格朗日曲率统计
Lagrangian Curvature Statistics from Gaussian Subensembles in Turbulent Flows
AI总结：
本研究针对湍流示踪粒子轨迹曲率的间歇性效应，推导了曲率概率密度函数的精确表达式与闭式近似，经实验验证吻合良好，且方法可扩展至等离子体湍流等复杂系统。
AI中文摘要：
远离转捩的完全湍流的一个显著特征是，在小时空尺度上会间歇性地出现极端波动，这些波动作为一种本质上的多尺度可观测量，会对示踪粒子轨迹的瞬时曲率产生定性和定量的影响。本文对湍流中示踪粒子轨迹的曲率进行了完整的统计描述，包含并量化了间歇性效应。我们推导了曲率概率密度函数的精确表达式和闭式近似，两者均与不同类型湍流的实验室实验数据吻合良好，可量化系统的通用行为，该方法可扩展至等离子体湍流等更复杂的系统。
英文摘要：
A salient feature of fully turbulent flows far from onset is the intermittent occurrence of extreme fluctuations at small spatial and temporal scales. These have a qualitative and quantitative effect on the instantaneous curvature of a tracer particle trajectory as an intrinsically multi-scale observable. Here, we provide a complete statistical description of the curvature of tracer particle trajectories in turbulent flows that includes and quantifies intermittency effects. We derive an exact expression and a closed-form approximation for the curvature probability density function, both agree well with data obtained from laboratory experiments of different types of turbulent flows, and quantify the generic behavior of the system. The method can be extended to more complex systems such as plasma turbulence.
