Generation of energy and vorticity production by surface waves through two-dimensional turbulence effects.

表面波通过二维湍流效应产生能量和涡量。

基本信息

批准号：
395843083
负责人：
Professorin Dr. Alexandra von Kameke
金额：
--
依托单位：
Heinrich-Blasius-Institut für Physikalische Technologien
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/395843083?language=en
关键词：
Generation energy vorticity production surface

项目摘要

The proposed study investigates energy condensation in quasi two-dimensional turbulence that is driven by surface waves. This physical mechanism is explored with regard to its potential for energy generation. In two-dimensional turbulence the net energy is transferred from small scales to large scales. Energy condensation develops when large scale friction is low and energy piles up at large scales. In this way, energy condensation produces large ordered flow structures from disordered small scale forcing that drives the two-dimensional turbulence. In her PhD-thesis the applicant Dr. von Kameke showed for the first time that two-dimensional turbulence can also be driven by surface waves. However, it is unclear if two-dimensional turbulence and energy condensation can also be driven by more naturally occurring unordered forcing as for instance provided by oceanic surface waves. It is not yet fully understood how non-breaking surface waves generate horizontal vorticity, and if the waves have to possess certain properties. Additionally, the necessary boundary conditions for energy condensation are vague. Also, it needs to be addresses if the process of energy condensation is stable to the introduction of further sources of drag, i.e., when a turbine is plugged into the fluid flow in order to retrieve energy. Here, these open points are to be investigated using a Faraday experiment where surface waves are caused by the shaking of a container with fluid. The generation of vorticity by the surface waves and the influence of the boundary- and forcing- conditions on energy condensation will be studied as well as the velocity statistics. For this end the full unsteady three-dimensional velocity field at the water surface and below the water surface needs to be recorded which has not been investigated so far. The latest optical methods will be used, such as time-resolved high speed planar particle image velocimetry and time-resolved three-dimensional (tomographic) particle image velocimetry. The complete velocity data set allows to doubtlessly verify, if the flow obtained in each case is two-dimensional and, if energy condensation takes place. Two-dimensionality is analyzed on the basis of energy and enstrophy spectral fluxes, calculated with the aid of a novel filtering method. Moreover, existing three-dimensional flow structures will be identified and characterized. The vertical velocity component will be compared to the horizontal motion. The forcing, exerted by the surface waves on the fluid-particles, and the resulting vorticity generation will be quantified by measuring the fluid surface elevation simultaneously to the PIV measurements and the subsequent usage of Lagrangian techniques that allow to correlate waves and particle movement. The objective of this study is to uncover a new effective mechanism to retrieve renewable energy and will broaden insight into surface wave physics and two-dimensional turbulence.

拟议的研究研究了由表面波驱动的准二维湍流中的能量凝结。探索了这种物理机制，就其产生能量的潜力进行了探讨。在二维湍流中，净能量从小尺度转移到大尺度。当大规模摩擦低并且能量堆积在大尺度上时，能量凝结就会发展。通过这种方式，能量凝结会产生大量的流量结构，从无序的小规模强迫驱动二维湍流。在她的博士学位中，申请人冯·卡梅克（Von Kameke）博士首次表明二维湍流也可以由表面波驱动。但是，尚不清楚二维湍流和能量凝结是否也可以由更自然发生的无序强迫驱动，例如由海洋表面波提供。尚不完全了解非破裂的表面波如何产生水平涡度，以及这些波是否必须具有某些特性。另外，能量冷凝的必要边界条件模糊。同样，如果能量冷凝的过程稳定在引入更多的阻力来源时，即当将涡轮机插入流体流中以获取能量时，则需要解决。在这里，将使用法拉第实验研究这些开放点，在该实验中，表面波是由流体摇动的容器引起的。将研究通过表面波以及边界和强迫条件对能量凝结的影响以及速度统计的产生。为此，需要记录到迄今为止尚未对水面和水面下方的完整不稳定的三维速度场。将使用最新的光学方法，例如时间分辨的高速平面粒子图像速度法和时间分辨的三维（层析成像）粒子图像速度法。完整的速度数据集毫无疑问地验证了在每种情况下获得的流量是否二维，并且是否发生了能量凝结。借助一种新型滤波方法计算得出的能量和肠情光谱通量，分析了二维性。此外，将确定和表征现有的三维流量结构。将垂直速度分量与水平运动进行比较。由表面波在流体粒子上施加的强迫，以及所得的涡度产生，将通过同时测量流体表面高度与PIV测量值以及随后使用Lagrangian技术的使用来量化，从而允许将波和粒子运动相关。这项研究的目的是发现一种新的有效机制来检索可再生能源，并将扩大对表面波理物理和二维湍流的了解。