MRI: Acquisition of Instrumentation on Experimental Studies on Interactions of Unsteady Flows and Dynamical Boundaries

这笔合同将使购买粒子成像速度系统(PIV)、通用研究显微镜、流变仪和一些较小的设备成为可能。有了这些仪器，研究人员将研究一些流体问题，这些问题涉及到非稳定流体流动与移动边界的相互作用。特别是，计划研究以规定波形拍打的刚性机翼的自由飞行。当机翼启动单向飞行时，PI将解决与早期阶段产生推力有关的问题。他们还将研究在飞行过程中能够俯仰的拍动机翼的影响，并将其性能与非俯仰机翼进行比较，以及与挥舞旗帜相关的不稳定性，以及强迫旗帜产生不同类型尾流结构的机制。这个实验将解决飘扬的旗帜和游动的鱼之间的联系和区别的问题。此外，众所周知，流体泵送和动物运动有许多共同的方面，可以用类似的理论处理来研究。这项计划中的研究将使用各向异性几何学(棘轮)来研究流体的传输，以及模型生物(线虫)在粘性流体中的游泳。这些研究将扩展到复杂的流体，因为即使在低雷诺数的情况下，这些系统也会发生非线性响应。所要求的仪器将实现应用数学实验室(AML)的根本改进，这将使研究流动流体中的动态边界问题变得更加精确和灵活。这些研究项目将涉及各级科学家，从教职员工到积极进取的本科生和高中生。

This award will make possible the purchase of a system of Particle Imaging Velocity (PIV), a universal research microscope, a rheometer and a few smaller equipments. With these instrumentations, the investigators will study a number of fluid problems that involve unsteady fluid flows interacting with mobile boundaries. In particular, it is planned to study the free flight of a rigid wing that is flapped at prescribed wave forms. The PIs will address questions related to the generation of thrust at early stages as the wing initiates a unidirectional flight. They will also study the effects of a flapping wing that is able to pitch during its flight, and compare its performance to a non-pitching wing, as well as the instability associated with flapping flags and the mechanism by which forced flags produce different types of wake structures. This experiment will address the question of the connections and differences between a flapping flag and a swimming fish. Moreover, it is well known that fluid pumping and animal locomotion share many common aspects, and can be studied using similar theoretical treatments. The planed study will investigate the transport of fluid using anisotropic geometry (ratchets) and the swimming of a model organism (C. elegans) in viscous fluids. The studies will be extended to complex fluids, since nonlinear responses take place in these systems even at low Reynolds numbers. The requested instrumentations will realize a fundamental improvement at the Applied Mathematics Laboratory (AML), which will allow the investigation of dynamical boundary problems in moving fluids with added precision and flexibility. The research projects will involve scientists at all levels, ranging from faculty members to motivated undergraduate and high-school students.