Linking topographic internal wave radiation to near-field processes, dissipation and mixing

智力优势：该项目解决了孤立地形特征上潮汐流的动力学问题，特别关注参数空间中的状态，其中非线性导致显著的局部混合和耗散，与总体能量平衡中的波辐射率相比。这种水流形态既发生在深海中，也发生在高而孤立的地形附近，如夏威夷山脊。一方面是近场耗散和混合，另一方面是远场辐射的相对重要性，在不同的地点有所不同，并取决于目前尚未很好理解的因素。主要目标是了解将非线性局部流动现象与远场波辐射的强度和特征联系起来的动力学，并将不同频率下的混合、耗散和辐射速率与表征流动和地形的参数联系起来。该项目将利用高分辨率的实验方法，在并行超级计算机上运行三维数值模拟。模拟将解决边界层分离和剪切不稳定等现象，以及大约十年的惯性子范围。数值模型是专门为这些面向过程的研究而设计的，它结合了高精度的数值方法和在分布式内存计算设施上的高效实现。更广泛的影响：地形上的分层流是海洋运动的一个基本方面，具有广泛的现象特征。产生向远场辐射的内波的过程可以共存，并与近场现象（如高阻力状态、内部水力跳变、耗散和混合）动态耦合。了解这些局部和全局响应之间的物理联系是能量转换成功参数化和内波驱动混合的重要前提。该项目将直接支持1名物理海洋学博士研究生的教育和培训。这项工作的一些方面将被纳入研究生课程，由研究人员在环境流体动力学和环境流动中的湍流中教授给物理海洋学，气候科学和机械与航空航天工程的学生。调查人员还将维持一个项目网页，传播数值工具，目的是使所有数值结果可由其他小组复制；有用的作为相关或扩展研究的起点；并且适合作为计算流体力学的教学实例。结果也将被整合到圣地亚哥飞行标准地区办公室关于波浪飞行和下坡水流危害的公开讲座中。

Intellectual Merit: The project addresses the dynamics of tidal flows over isolated topographic features, focusing in particular on the regime in parameter space where nonlinearity leads to significant local mixing and dissipation in comparison to the rate of wave radiation in the overall energy balance. This flow regime occurs both in the deep ocean and also near tall isolated features such as the Hawaiian Ridge. The relative importance of near-field dissipation and mixing on the one hand, and radiation to the far-field on the other, varies between sites and depends on factors that are not presently well understood. The primary objective is to understand the dynamics linking nonlinear local flow phenomena to the intensity and character of wave radiation to the far field and to relate the rates of mixing, dissipation and radiation at various frequencies to parameters characterizing the flow and the topography. The project will utilize an experimental approach using high-resolution, three-dimensional numerical simulations run on parallel supercomputers. The simulations will resolve phenomena such as boundary layer separation and shear instabilities and about a decade of the inertial sub-range. The numerical model was designed specifically for process-oriented studies such as these and combines high-accuracy numerical methods with efficient implementation on distributed memory computing facilities. Broader Impacts: Stratified flow over topography is a fundamental aspect of oceanic motion characterized by a wide range of phenomenology. The processes that produce internal waves that radiate to the far field can coexist and be dynamically coupled to near-field phenomena such as high-drag states, internal hydraulic jumps, dissipation and mixing. Understanding the physics linking these local and global responses is an important precursor to the successful parameterization of energy conversion and therefore internal wave driven mixing. The project will directly support the education and training of one Ph.D. student in Physical Oceanography. Aspects of this work will be incorporated into graduate classes taught by the investigators in Environmental Fluid Dynamics and Turbulence in Environmental Flows to students in Physical Oceanography, Climate Sciences and Mechanical and Aerospace Engineering. The investigators will also maintain a project web page disseminating numerical tools with the objective of making all of the numerical results: reproducible by other groups; useful as a starting point for related or extended studies; and suitable as educational examples of computational fluid mechanics. Results will also be integrated into public lectures given through the San Diego Flight Standards District Office on wave flights and the hazards of down slope flows.