ITR/AP (GEO): High Resolution Parallel Coastal Ocean Modeling

多个计算和数值工具将被合成，产生一个创新和强大的沿海海洋模拟工具。该项目的主要目标是采用数值大涡模拟，在非流体静力和地形跟随表示必不可少的条件下，对沿海海洋的运动和运输进行准确预测。该模型应该能够处理从自由表面到河床的所有过程，以便能够模拟从表面波到内波到沉积物运动的整个范围。第二个目标是应用现有的最佳算法来创建能够或表示高分辨率物理过程的仿真代码，并且能够在多处理器并行计算机上实现非常高的速度。项目代码将从现有的非结构网格上非静力自由表面流动的半隐式数值代码演变而来。该代码基于三维非定常Navier-Stokes方程，采用了一种鲁棒、稳定、高效的半隐式算法。然而，现有的代码是为系列机器开发的，缺乏沿海海洋应用的一些重要元素，例如，标量或物质运输模块，用于大涡模拟的最先进的子滤波尺度模型，以及对水深或沿海边界的高分辨率处理。这项工作的重点是并行化代码并安装适当的算法，以满足准确表示物理的需要，以及为沿海地区生成快速和健壮的生产代码的需要。一个基本的概念是将沿海模拟无缝嵌入到更大规模的模拟中，以便在整个领域周围应用自然边界条件。不使用人工设备来过滤模拟，以避免代码不稳定或边界反射。非结构化网格将在水平面上使用，允许精确表示水深和海岸特征，这需要从一个子域到另一个子域的网格密度发生严重变化。复合网格方法将用于拟合地形跟踪的高分辨率网格，并将其连接到内部域。完成的代码的两个具体应用计划。两者都涉及内部潮汐的非流体静力演化。第一个是在加利福尼亚州的蒙特利湾，那里预计会形成孤子，并且在蒙特利峡谷的底部，内部潮汐信号会增强。第二个是在夏威夷的马马拉湾，在那里观察到高振幅和非线性的内部潮汐，关于这些波的性质及其在海湾中的行为有一些关键问题需要回答。本工作的贡献包括：高性能：使用消息传递接口MPI并行实现；非静水压力优化的非结构网格三维并行求解器代码特点：基于TVD法的非结构化网格精确平流；基于完全验证的子滤波尺度运动速度估计方法的非静力大涡模拟最先进的网格生成（水平非结构化），用于复杂水深测量和海岸边界的精确分辨率，以及嵌入式底部跟踪网格；自由表面采用半隐式处理；和生产风格：详细的用户手册，说明使用沿海-海洋尺度模拟的代码

0113111 Street A number of computational and numerical tools will be synthesized to produce an innovative and powerful coastal ocean simulation tool. The primary goal of the project is to employ numerical large-eddy simulation to generate accurate predictions of motions and transport in coastal oceans under conditions when a non-hydrostatic and terrain-following representation is essential. The model should be able to handle all processes from the free surface to the bed so that the whole range from surface waves through internal waves to sediment motions can be simulated. The second goal is to apply the best algorithms available to create a simulation code that is capable or representing the physical processes at high resolution and capable of very high speed on multiple processor parallel computer. The project code will evolve from an existing semi-implicit numerical code for nonhydrostatic free-surface flows on unstructured grids. The code is based on the three-dimensional unsteady Navier-Stokes equations and utilizes a semi-implicit algorithm that is robust, stable, and very efficient. However, the existing code was developed for serial machines and lacks a number of important elements for the coastal ocean application, e.g., a scalar or material transport module, state-of-the-art subfilter-scale models for large-eddy simulation, and a highly-resolved treatment of the bathymetric or coastal boundaries. The focus of this work is to parallelize the code and install appropriate algorithms to meet both the need to represent the physics accurately and the need to produce a fast and robust production code for the coastal zone. A fundamental concept will be to seamlessly imbed the coastal simulations in larger-scale simulations so that natural boundary conditions would be applied around the entire domain. No artificial devices would be used to filter the simulations to avoid code instabilities or boundary reflections. The unstructured grid will be employed in horizontal planes allowing accurate representation of bathymetric and coastal features, which require severe changes in grid density from one subdomain to another. The composite grid method will be employed to fit a terrain-following highly resolved grid over the bathymetry and linked to the interior domain. Two specific applications of the completed code are planned. Both involve nonhydrostatic evolution of internal tides. The first is in Monterey Bay, California, where solitons are expected to form and the internal tide signal is intensified in the bottom of the Monterey Canyon. The second is in Mamala Bay, Hawaii, where high-amplitude and nonlinear internal tides are observed and there are key questions to be answered about the nature of these waves and their behavior in the Bay. The contributions on this work include: High performance: Parallel implementation using MPI, the message passing interface; Optimized unstructured-grid, 3D parallel-solver for the nonhydrostatic pressure; Code Features: Accurate advection based on the TVD method for unstructured grids; Nonhydrostatic large-eddy simulation with a fully-validated velocity estimation method for subfilter-scale motions; State-of-the-art grid generation [unstructured in the horizontal] for accurate resolution of complex bathymetry and shore boundaries and an embedded bottom following grid; Free surface using a semi-implicit treatment; and Production-style: Detailed users' manual that illustrates the use of the code for coastal-ocean scale simulations