Particle Image Baro-Velocimetry (PIBV): simultaneous measurement of pressure and velocity in fluids

Porfii，Maurizio 1332204这项提议解决了首次实现对流体流动中的瞬时压力和速度的直接和同时的全场测量这一重大挑战。拟议的方法将改变目前的实验流体力学实践，为美国的学术、工业和政府机构提供实时执行流体流动的运动学和动力学的本地传感的能力。虽然拟议的框架在本质上是变革性的，但其实际实施只需要对现有的流体力学测量系统进行最小程度的升级。具体地说，这项建议包括将新型压敏示踪剂颗粒配方并纳入传统的粒子图像测速(PIV)系统，以实现新型粒子图像气压测速(PIBV)系统。建议的微胶囊将包括高度顺应的生物相容性水凝胶壳中的空气包裹，这些水凝胶壳是专门配制成具有不同波长分布的荧光，即根据水凝胶壳的应变改变颜色。作用在颗粒上的压力改变了它的体积，这反过来又导致荧光反应的可测量变化。探头对压力阶跃变化的响应时间预计在微秒量级。此外，水凝胶微探头的设计可以为实验量身定做，以在规定的压力范围内优化灵敏度，并检测低至10帕斯卡的压力水平。利用这些新的微尺度粒子作为示踪剂，可以使用传统的PIV技术测量流体中的速度场，而不会损失流动跟踪的保真度或增加总体测量的不确定度。智能价值：该项目的智能优点包括：(I)建立一种新的测量系统，将能够全面表征复杂流体流动场景的压力和速度场；(Ii)设计、合成和校准一类基于水凝胶的新型生物兼容压力微探头；(Iii)建立和实验验证基于力学的气包水凝胶微球的理论和计算模型；以及(Iv)在仿生推进、流体动力阻尼和内部流动的最新研究中通过直接压力测量来评估PIBV的潜力。广泛的影响：同时表征流动运动学和动力学的有效技术将造福于学术、工业和政府机构的多个科学和工程团体，并对几个应用和基础研究领域产生积极影响。该项目将加强对纽约布鲁克林社会经济多元化学生群体的技术培训和教育。通过与现有的NSF项目(RET SITE和GK-12项目)的协同，将开发一套用于初中生和高中生演示流体力学各种原理的教学模块，并在课堂教学中实施。该项目还将通过支持滑铁卢大学美国学生的暑期研究体验，帮助消除极端学生群体的心理障碍，这些学生定义了布鲁克林和安大略省滑铁卢的大都市和农村背景。纽约大学理工学院将举办为期一天的PIBV系统教学短期课程，重点介绍测量原理和不确定度、数据采集和处理以及与PIV系统的集成。将开发一个关于该项目的维基页面，以向公众宣传和宣传PIBV。

Porfiri, Maurizio 1332204 This proposal addresses the grand challenge of enabling, for the first time, direct and simultaneous full-field measurement of the instantaneous pressure and velocity in a fluid flow. The proposed methodology will transform current experimental fluid mechanics practices by providing US academic, industrial, and government institutions with the capability of performing local sensing in real time of kinematics and kinetics of fluid flow fields. While the proposed framework is transformative in nature, its practical implementation requires minimal upgrades to established fluid mechanics measurement systems. Specifically, this proposal encompasses the formulation and incorporation of novel pressure-sensitive tracer particles into traditional Particle Image Velocimetry (PIV) systems towards a novel Particle Image Baro-Velocimetry (PIBV) system. The proposed microcapsules will comprise air encapsulated in highly compliant biocompatible hydrogel shells that are specifically formulated to fluoresce with different wavelength distributions, that is, to change color, depending on the strain of the hydrogel shell. Pressure acting upon the particle modifies its volume, which, in turn, results in a measurable change in the fluorescent response. The response time of the probes to a step change in pressure is expected to be on the order of a microsecond. Further, the hydrogel microprobe design can be tailored to the experiment to optimize sensitivity over a prescribed pressure range and detect pressure levels as low as the order of ten pascals. Utilizing these novel microscale particles as tracers, the velocity field within a fluid can be measured using traditional PIV techniques without a loss of flow tracing fidelity or an increase in overall measurement uncertainty.Intellectual Merit :The intellectual merits of this project include: (i) establishing a novel measurement system that will enable full characterization of the pressure and velocity fields of complex fluid flow scenarios; (ii) designing, synthesizing, and calibrating a new class of biocompatible pressure microprobes based on hydrogels; (iii) formulating and experimentally validating mechanics-based theoretical and computational models of air-encapsulated hydrogel spheres in fluids; and (iv) assessing PIBV potential through direct pressure measurement in state of the art studies on biomimetic propulsion, hydrodynamic damping, and internal flows.Broader Impacts :Effective technologies for simultaneous characterization of flow kinematics and kinetics will benefit multiple scientific and engineering communities within academic, industrial, and government institutions and positively impact several applied and fundamental research fields. This project will reinforce technical training and education of the socioeconomically diverse student body in Brooklyn, New York. A suite of teaching modules for middle and high school students demonstrating various principles of fluid mechanics will be developed and implemented in classroom education through synergy with current NSF programs (RET site and GK-12 program). The project will also contribute to the removal of mental barriers across the extremal student populations defining the spectrum of metropolitan versus rural backgrounds in Brooklyn and Waterloo, Ontario by supporting the summer research experience for US students in the University of Waterloo. A one-day instructional short course on PIBV systems will be hosted at the Polytechnic Institute of New York University with emphasis on the measurement principle and uncertainty, data acquisition and processing, and integration into PIV systems. A wiki page about the project will be developed for outreach to the public and promoting PIBV.