Laboratory Experiments on Nonlinear Waves and Turbulence

非线性波和湍流的实验室实验

• 批准号: 0229614
• 负责人: John Hart
• 金额: $ 34.83万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0229614&HistoricalAwards=false
• 关键词: Laboratory; Experiments; Nonlinear; Waves; Turbulence

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.

实验室实验在三种流体系统上进行，这些流体系统表现出陆地和行星大气动力学中重要的过程：（1）由差动旋转盖驱动的旋转圆柱体中的非线性波和湍流。 该系统中的不稳定性导致旋转波因具有尖角而偏离光滑的圆形或椭圆形。 这些所谓的“多边形”波在外观上与在飓风眼墙和土星极地大气中观察到的波相似。 (2) 旋转水跃中的不稳定性和波浪形成。 旋转流出层中的圆形水跃是形成多边形波的另一种机制。 (3)湍流旋转对流进动平均流的结构与力学。 涡流应力和平均流量剖面的直接测量将解释旋转湍流对流中平均流量产生的机制。这些实验提供了类似于大气中的非线性流量的数据，而这些数据很难通过任何其他方式获得。 此外，它们还提供了评估地球物理流大涡模拟 (LES) 中小规模湍流参数化所需的信息。 受控实验室实验涉及类似于大气中的约束（特别是旋转和分层），提供了有价值的试验场。 这些和类似的实验室实验用于研究生和本科生课程，以演示与大气科学相关的基本流体过程。