Internal gravity wave dynamics in a rotating and stratified fluid

Swinney内部重力波在湖泊、海洋和大气中普遍存在，这是由于这些环境流体中存在密度分层。重力内波影响声波传输、泥沙输运和近海平台。这些海浪也是大洋环流的主要驱动机制。这项研究的目的是利用实验室实验和数值模拟来更好地了解内部重力波产生、相互作用和破裂背后的基本流体动力学。实验将在分层和旋转的流体中进行，使用粒子图像测速仪、电导探针和荧光染料可视化。伪谱数值实验将是对实验室实验的补充。具体地说，PIS将研究内部重力波-波相互作用产生的谐波，倾斜边界上的内波产生和混合，以及参数次谐不稳定的纬度相关性。在不存在适当的理论模型和现场观测提供稀疏数据的情况下，将获得详细的时空数据。在实验和模拟中系统地改变参数将有助于揭示潜在的物理现象。非共振波-波相互作用的实验将改善当前波与波之间能量交换的图景。关于内波产生的实验将量化一种新的机制，这种机制可以在湖泊和大陆边缘产生强烈的边界流和湍流混合。参数亚谐不稳定性的实验将有助于理解海洋中的全球重力内波耗散。对这项研究揭示的基本物理学的理解将增强量化内部重力波在湖泊、海洋和大气动力学中的作用的能力。除了环境应用，非共振波-波相互作用的实验也可能影响对强磁化等离子体中波的理解，其中存在与内部重力波具有相同色散关系的波(例如，托卡马克中的波)。此外，这种类型的波在白矮星和中子星的动力学中起着重要作用。

CBET-0755114Swinney Internal gravity waves are ubiquitous in lakes, oceans and the atmosphere, due to the density stratification present in these environmental fluid bodies. Internal gravity waves affect acoustic transmission, sediment transport and off-shore platforms. These waves are also a major driving mechanism for the general circulation of the ocean. The goal of this research is to use laboratory experiments and numerical simulations is to better understand the fundamental fluid dynamics underlying the generation, interaction and breaking of internal gravity waves. The experiments will be conducted in a stratified and rotating fluid using Particle Image Velocimetry, a conductivity probe, and fluorescent dye visualization. Pseudo-spectral numerical experiments will complement the laboratory experiments. Specifically, the PIs will study harmonic wave generation by internal gravity wave-wave interactions, internal wave generation and mixing over a sloping boundary, and latitudinal dependence of the parametric subharmonic instability. Detailed spatiotemporal data will be obtained in regimes where appropriate theoretical models do not exist and field observations provide sparse data. Systematic variation of parameters in the experiments and simulations will help reveal the underlying physics. Experiments on nonresonant wave-wave interactions will improve the current picture of energy exchange between waves. Experiments on internal wave generation will quantify a new mechanism that can produce strong boundary flow and turbulent mixing in lakes and continental margins. Experiments on the parametric subharmonic instability will help to understand the global internal gravity wave dissipation in oceans. Understanding of the fundamental physics revealed by this research will enhance the ability to quantify the role of internal gravity waves in lake, oceanic and atmospheric dynamics. Besides the environmental applications, experiments on nonresonant wave-wave interactions may also have impact on the understanding of waves in strongly magnetized plasmas, where there exist waves (e.g., in tokamaks) with the same dispersion relation as internal gravity waves. Further, this type of wave plays an important role in the dynamics of White Dwarfs and Neutron Stars.