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聚。人们探索了这种物理机制的能量产生潜力。在二维湍流中，净能量从小尺度转移到大尺度。当大尺度摩擦力较低并且能量在大尺度上堆积时，就会发生能量凝聚。通过这种方式，能量凝聚从驱动二维湍流的无序小尺度强迫中产生大的有序流结构。申请人冯·卡梅克博士在她的博士论文中首次证明，二维湍流也可以由表面波驱动。然而，尚不清楚二维湍流和能量凝聚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的强迫。目前尚未完全了解非破碎表面波如何产生水平涡度，以及波是否必须具有某些特性。此外，能量凝聚的必要边界条件也很模糊。此外，还需要解决能量凝结过程是否对于引入其他阻力源（即当涡轮机插入流体流以回收能量时）稳定的问题。在这里，将使用法拉第实验来研究这些开放点，其中表面波是由装有液体的容器的振动引起的。将研究表面波产生的涡度以及边界条件和强迫条件对能量凝聚的影响以及速度统计。为此，需要记录水面和水面以下的完整非定常三维速度场，但迄今为止尚未进行研究。将使用最新的光学方法，例如时间分辨高速平面粒子图像测速和时间分辨三维（断层）粒子图像测速。完整的速度数据集可以毫无疑问地验证每种情况下获得的流量是否是二维的以及是否发生能量凝聚。二维性是在能量和熵谱通量的基础上进行分析的，并借助一种新颖的滤波方法进行计算。此外，现有的三维流动结构将被识别和表征。垂直速度分量将与水平运动进行比较。表面波对流体颗粒施加的力以及由此产生的涡量将通过在 PIV 测量的同时测量流体表面高度以及随后使用允许将波和颗粒运动关联起来的拉格朗日技术来量化。这项研究的目的是揭示一种新的有效机制来回收可再生能源，并将拓宽对表面波物理和二维湍流的认识。