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Electro-hydro-elastic modeling of Structure-Borne Traveling Waves and their application to aquatic swimming motions
Journal of Fluids and Structures ( IF 3.4 ) Pub Date : 2021-02-13 , DOI: 10.1016/j.jfluidstructs.2021.103230
Patrick F. Musgrave

Structure-Borne Traveling Waves (SBTWs) can replicate the combined undulatory and oscillatory motions utilized by body and/or caudal fin (BCF) aquatic swimmers. However, when SBTWs are generated in a dense fluid media, such as water, there is poor understanding of the Fluid–Structure Interactions (FSI). There is also limited understanding of how to achieve the full undulatory motions. This study demonstrates the effect of FSI on SBTWs and investigates the relationship between SBTW quality (undulatory vs. oscillatory motion) and forcing input. SBTWs function by leveraging a surface’s structural properties (mode shapes and natural frequencies) to deform a surface into a dynamic waveform. SBTWs are a combination of traveling and standing waves, and can range in quality from pure traveling wave (undulatory) to pure standing wave (oscillatory). SBTWs require a small number of actuators, can be generated on any thin-walled surface (flat or curved), and have customizable parameters (direction, frequency, wavelength). However, SBTWs are sensitive to FSI due to their dependence on the structural properties. In this study, an electro-hydro-elastic (EHE) model is developed to capture the effect of FSI on SBTWs and investigate how the forcing input affects the resultant waveform (undulatory vs. oscillatory). The EHE model consists of a clamped-free beam with discrete, piezoelectric actuators in a quiescent fluid. Slender beam theory and the hydrodynamic function are used to capture the added fluid mass and viscous damping, assuming small displacement amplitudes. The model accurately replicates experimental SBTWs in quiescent water across a range of parameters and is able to predict the SBTW quality. It is shown that the quality is maximized (i.e. pure traveling wave/undulatory motion) when the actuators provide equal forcing to the structure. This can be achieved through judicious actuator placement and control of the relative voltage inputs. This study demonstrates that SBTWs can be generated in quiescent water and they can replicate the combined undulatory and oscillatory motions seen in BCF swimming. This represents a critical step towards implementing SBTWs for underwater propulsion, and future studies should evaluate the propulsive capabilities (i.e. thrust).



中文翻译:

结构-波恩行波的电-水-弹性建模及其在水上运动中的应用

结构型行波(SBTW)可以复制身体和/或尾鳍(BCF)水上游泳者利用的组合波动和振荡运动。但是,当在诸如水之类的稠密流体介质中生成SBTW时,人们对流固耦合(FSI)的了解就很少。对于如何实现完整的起伏运动也知之甚少。这项研究证明了FSI对SBTW的影响,并研究了SBTW质量(波动与振荡运动)与强迫输入之间的关系。SBTW通过利用表面的结构特性(模式形状和固有频率)将表面变形为动态波形而起作用。SBTW是行波和驻波的组合,其质量范围可以从纯行波(波动)到纯驻波(振荡)。SBTW需要少量的执行器,可以在任何薄壁表面(平坦或弯曲)上生成,并具有可自定义的参数(方向,频率,波长)。但是,SBTW由于对结构特性的依赖性而对FSI敏感。在这项研究中,开发了一种电-水-弹性(EHE)模型来捕获FSI对SBTW的影响,并研究强制输入如何影响合成波形(波动的与振荡的)。EHE模型由在静止流体中具有离散压电致动器的免夹紧梁组成。假设梁的位移幅度较小,可以使用细长梁理论和流体力学函数来捕获增加的流体质量和粘性阻尼。该模型准确地复制了静态水中各种参数范围内的实验性SBTW,并能够预测SBTW的质量。结果表明,当执行器对结构施加相同的作用力时,质量就达到了最大化(即纯的行波/波动运动)。这可以通过明智地放置执行器和控制相对电压输入来实现。这项研究表明,SBTWs可以在静止的水中产生,并且可以复制BCF游泳中看到的波动和振荡运动的组合。这是为水下推进实施SBTW的关键一步,未来的研究应评估推进能力(即推力)。当执行器向结构提供相等的受力时(纯的行波/波动运动)。这可以通过明智地放置执行器和控制相对电压输入来实现。这项研究表明,SBTWs可以在静止的水中产生,并且可以复制BCF游泳中看到的波动和振荡运动的组合。这是为水下推进实施SBTW的关键一步,未来的研究应评估推进能力(即推力)。当执行器向结构提供相等的受力时(纯的行波/波动运动)。这可以通过明智地放置执行器和控制相对电压输入来实现。这项研究表明,SBTWs可以在静止的水中产生,并且可以复制BCF游泳中看到的波动和振荡运动的组合。这是为水下推进实施SBTW的关键一步,未来的研究应评估推进能力(即推力)。

更新日期:2021-02-15
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