MRI: Development of Pneumatic Water Wave Genesis, a versatile wavemaker for the UNC Joint Fluids Lab

MRI：开发气动水波起源，这是北卡罗来纳大学联合流体实验室的多功能造波机

• 批准号: 1229471
• 负责人: Roberto Camassa
• 金额: $ 65.54万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1229471&HistoricalAwards=false
• 关键词: MRI; Development; Pneumatic; Water; Wave

The goal of this project is to develop a potentially transformative new surface and internal wave-making method, based on a novel pneumatic concept with no mechanical actuators, and use it to dramatically extend the range of scientific research activities taking place in the UNC Joint Fluids Lab modular wavetank. The investigators intend to demonstrate feasibility of a method for excitation of a general family of gravity waves in non-uniform incompressible fluids. The method uses an array of independently controlled monopole flux sources arranged to provide a flux boundary condition over an arbitrary 2D manifold. The tangible results of the development will be a wave generating apparatus for use in an existing 0.75[m] wide by 36[m] long wave tank containing water with prescribed salt-stratified density profiles. The generator will excite a 1[m] by 0.75[m] rectangular boundary comprising N independent rectangular flux sources, each being 0.75[m] wide by 1/N[m] high, stacked up vertically. This boundary is inserted into a wave tank to form one end of an active flume. Each source will drive a near-spatially-uniform volume velocity over its aperture. Wave modes of zeroth horizontal order and up to (N-1)th vertical order can thereby be excited. The proposed design was inspired by a recently developed mechanical actuator system designed at ENS-Lyon (Gostiaux et al. 2007) to produce monochromatic plane waves. However, the proposed apparatus will go well beyond this design, by doing away with the mechanical moving parts, and substituting displacement chambers driven with air pressures generated by feedback-controlled pneumatic exciters capable of following arbitrary band-limited control signals. This allows generation of arbitrary vertical excitation profiles, including but not limited to superpositions of monochromatic plane waves of differing periods and directions. This design will further enable other interesting excitations, including non-periodic or even non repetitive impulse profiles. In the future, this general excitation method can in principle extend these capabilities to fully 2D boundary flux conditions, by tessellating an arbitrarily shaped boundary surface.Both surface waves and their less widely known internal counterparts, which can occur for example in layers between fresh and salt water, have properties of more significant consequences than are generally appreciated. To name a few, the spontaneous development of a rogue wave can sink a ship; the formation and development of a Tsunami as it propagates in open water and upon landfall such as in a harbor can wreak havoc in some places while leaving others relatively unscathed; and the effects of internal waves on mixing stratified salt and fresh water layers contributes to the ecological health of an estuary and the well being of the species inhabiting it. A substantial body of theory continues to be developed to understand these so-called gravity wave behaviors and to render them predictable, by turning guesswork into solid physical and engineering mathematical models useful in naval architecture, disaster prediction, environmental impact, among many other areas of application. But precisely how good are these theories? Fundamental to the Scientific Method is experimental verification, and gravity wave mechanics is no exception. The problem addressed by this project is that of finding a method to repeatably generate and controllably vary the conditions in a laboratory environment equivalent to natural phenomena such as rogue waves. Often, theories pertaining to such phenomena undergo only limited testing, leaving the naval, environmental and ecological engineering decisions based thereon vulnerable to error. Making waves is easy: drop a stone in a wavetank. Creating the exact conditions to excite a rogue wave in a tank, and exploring how varying parameters affects the behavior or even the existence of such a wave requires an exquisite degree of finesse in controlling these conditions. The aim of this project is to develop a wavemaker for excitation of a general family of gravity waves in non-uniform incompressible fluids, thereby enabling experimental exploration in a controlled laboratory environment of real world phenomena having social and engineering relevance.

该项目的目标是开发一种具有潜在变革性的新表面和内部造波方法，该方法基于无机械致动器的新型气动概念，并使用它来大幅扩展在WATCHJoint Fluids Lab模块化波箱中进行的科学研究活动的范围。研究人员打算证明在非均匀不可压缩流体中激发一般重力波族的方法的可行性。该方法使用一个阵列的独立控制的磁通源的安排，以提供一个通量的边界条件，在任意的二维流形。开发的有形成果将是一种波浪发生装置，可用于现有的0.75[m]宽× 36[m]长的波浪槽，该波浪槽含有具有规定盐层密度分布的水。发生器将激励1[m] × 0.75[m]的矩形边界，该矩形边界包括N个独立的矩形通量源，每个通量源为0.75[m]宽× 1/N[m]高，垂直堆叠。将此边界插入波浪水槽中，形成活动水槽的一端。每个源将在其孔径上驱动接近空间均匀的体积速度。从而可以激发水平零阶和垂直（N-1）阶的波模。 拟议的设计灵感来自最近开发的机械致动器系统设计在ENS-Lyon（Gostiaux等人，2007年），以产生单色平面波。然而，所提出的装置将远远超出这种设计，通过取消机械运动部件，并取代位移室，位移室由能够遵循任意带限控制信号的反馈控制气动激励器产生的空气压力驱动。这允许生成任意垂直激发轮廓，包括但不限于不同周期和方向的单色平面波的叠加。 该设计将进一步实现其他感兴趣的激励，包括非周期性或甚至非重复性脉冲轮廓。在未来，这种通用的激励方法可以在原则上扩展这些功能，以完全二维边界通量条件下，通过镶嵌一个任意形状的边界surface.Both表面波和他们的不太广为人知的内部对应物，这可能会发生在层之间的淡水和盐水，具有更显着的后果比一般理解的属性。 举几个例子，一个流氓波的自发发展可以沉没一艘船;海啸的形成和发展，因为它在开放水域传播，并在登陆时，如在港口，可以在一些地方肆虐，而让其他人相对毫发无损;内波对咸淡水混合层的影响有助于河口生态健康和物种的生存大量的理论继续被开发，以理解这些所谓的重力波行为，并通过将猜测转化为在海军建筑、灾害预测、环境影响以及许多其他应用领域中有用的可靠的物理和工程数学模型来使它们可预测。 但这些理论究竟有多好呢？ 科学方法的基础是实验验证，重力波动力学也不例外。 该项目解决的问题是找到一种方法，在实验室环境中重复产生和可控地改变相当于自然现象（如流氓波）的条件。通常，与这种现象有关的理论只经过有限的测试，使海军，环境和生态工程决策的基础上容易出错。 制造波浪很简单：在波浪池里扔一块石头。 要在坦克中创造激发异常波的确切条件，并探索不同参数如何影响这种波的行为甚至存在，需要在控制这些条件方面有相当高的技巧。 该项目的目的是开发一种造波器，用于激发非均匀不可压缩流体中的一般重力波族，从而在受控的实验室环境中对具有社会和工程相关性的真实的世界现象进行实验探索。