Development and Deployment of a Versatile In Situ Underwater Miniature PIV System (UWMPIV)

粒子图像测速技术(PIV)是表征小尺度湍流结构的理想技术，如湍流动能耗散率(TKE)、应变率和涡量。然而，由于对高功率激光器、高性能CCD相机和成熟的图像采集计算机系统的要求，它很难适应野外研究，这些都不适合潜水式结构。PI提出了一种替代解决方案，使用由电池供电的IIIb类二极管泵浦的固态(DPSS)激光器。通过引导连续波激光光束通过转镜产生光片，从而确保有足够的光能照射自然水域中的小颗粒(~10 mm至~100 mm)，同时保持颗粒的曝光时间较短，以避免图像模糊。初步的系统已经建成，配备了一台超移动计算机和一个基于USB的信号发生器。皮？S建议对原型系统进行改进，使其能够测量更高速度和湍流度的流动，并能根据平均流动方向的变化来调整其定向，以避免平面外运动引起的测量误差。改进后的系统将是紧凑的，多功能的，并允许长期观察(几天)。UWMPIV将被设置为一个自由漂浮系统，测量小尺度湍流结构的垂直剖面，包括耗散率、拟能和紧接在空气-水界面下方的表面散度。其目的是提供对自由表面湍流及其对通过空气-水界面的气体传输的影响的了解。更广泛的影响：私人投资机构在概述这一紧凑的现场PIV系统将如何用于教育和公共宣传方面做得非常好。除了用于各种土木工程课程的实验室和案例研究外，该提案还为两名研究生提供了资金。与威斯康星州码头探索世界的合作听起来是接触公众的绝佳机会。PIV可以提供一个非常不同的海洋流动视角，因为它以非常详细的方式解析2D场。这在典型的海洋观测中很少实现，因为海洋观测通常是稀疏的。

Particle Image Velocimetry (PIV) is an ideal technique to characterize turbulent flow structures at smaller scales, such as the dissipation rate of turbulent kinetic energy (TKE), rate of strain, and vorticities. It is, however, difficult to be adapted to field studies due to the requirement of high power lasers, high performance CCD cameras and full-fledged image acquisition computer systems, which are not suitable for submersible configurations. The PI's propose an alternative solution by using a class IIIb Diode Pumped Solid State (DPSS) laser which is powered by batteries. A light sheet is created by steering the continuous-wave laser beam through a rotating mirror, thus ensuring adequate light energy for illuminating small particles (~10 mm to ~100 mm) in natural waters while at the same time keep the exposure time of particle short to avoid blurred images. A preliminary system has been built with an ultra-mobile computer and a USB-based signal generator. The PI?s propose to improve the prototype UWMPIV system, so it can measure flows with higher speed and turbulence level and can adapt its orientation with shifting mean flow direction to avoid measurement error induced by out-of-plane motions. The improved system will be compact, versatile and allow for long-term observations (several days). The UWMPIV will be set up as a free-floating system that measures the vertical profiles of small-scale turbulence structures, including the dissipation rate, enstrophy and surface divergence immediately below the air-water interface. The purpose is to provide understanding of free surface turbulence and its effects on gas transfer through the air-water interface. Broader Impacts:The PIs do a very good job of outlining how this compact in-situ PIV system will be used in education and public outreach. As well as being used for labs and case studies in various civil engineering courses, the proposal has money for two graduate students. The collaboration with Discovery World at Pier Wisconsin sounds like an excellent opportunity to reach the public. PIV could provide a very different perspective of ocean flows, as it resolves 2D fields with exceptional detail. This is very seldom achieved with typical ocean observations, which are generally sparse.