Laboratory Experiments on Nonlinear Waves and Turbulence

本文对三个流体系统进行了室内实验，这些系统体现了地球和行星大气动力学中重要的过程：(1)由差动盖驱动的旋转圆柱体中的非线性波和湍流。该系统的不稳定性导致旋转波偏离光滑的圆形或椭圆形状，具有尖锐的角。这些所谓的“多边形”波在外观上与飓风眼壁和土星极地大气中观察到的波相似。(2)旋转水跃的不稳定性和波浪形成。旋转流出层中的圆形水力跃变是形成多角形波浪的另一种机制。(3)湍流旋转对流中处理平均流的结构和力学。直接测量涡旋应力和平均流动剖面将解释旋转湍流对流中平均流动的产生机制。这些实验提供了与大气中类似的非线性流动的数据，这些数据很难用任何其他方法获得。此外，它们还提供了在地球物理流动大涡模拟（LES）中评估小尺度湍流参数化所需的信息。受控的实验室实验涉及与大气中类似的约束条件（特别是旋转和分层），提供了一个有价值的试验场。这些和类似的实验室实验用于研究生和本科生的课堂，以演示与大气科学相关的基本流体过程。

Laboratory experiments are carried out on three fluid systems that manifest processes important in the dynamics of terrestrial and planetary atmospheres: (1) Nonlinear waves and turbulence in a rotating cylinder driven by a differentially rotating lid. Instabilities in this system lead to rotating waves that deviate from smooth circular or elliptical shape by having sharp corners. These so-called "polygonal" waves are similar in appearance to waves observed in hurricane eyewalls and in the polar atmosphere of Saturn. (2) Instability and wave formation in a rotating hydraulic jump. A circular hydraulic jump in a rotating outflow layer is an alternative mechanism for the formation of polygonal waves. (3) The structure and mechanics of precessing mean flows in turbulent rotating convection. Direct measurements of eddy stresses and mean flow profiles will explain the mechanism of mean-flow generation in rotating turbulent convection.These experiments provide data on nonlinear flows analogous to those in the atmosphere that are difficult to obtain by any other means. Moreover, they give the information needed to evaluate small-scale turbulence parameterization in large-eddy simulations (LES) of geophysical flows. Controlled laboratory experiments that involve constraints similar to those in the atmosphere (particularly rotation and stratification) provide a valuable testing ground. These and similar laboratory experiments are used in graduate and undergraduate classes to demonstrate fundamental fluid processes of relevance to atmospheric science.