基于SPH方法的涌潮水动力与局部冲淤数值模拟研究

A tidal bore is a spectacular hydrodynamic phenomenon which is commonly formed in the funnel-shaped estuaries with large tidal range during the spring tide. The Qiantang River Tidal Bore in the Hangzhou Bay is one of the most famous, known for its tremendous momentum, as well as the natural scenarios and historical culture. However, the powerful energy of the tidal bore is also a severe threat to the security of civilians and facilities along the river. In this project, a small scale numerical model for the simulation of tidal bore, river bed and structures interaction will be implemented based on a meshfree method called Smoothed Particle Hydrodynamics (SPH). The propagation and evolution of the tidal bores will be represented, taking advantage of SPH method in dealing with highly nonlinear and distorted free surface and multi-phase flows. The coupled water-sediment simulation will be achieved owing to the Lagrangian feature of SPH method. This project will reveal the small scale hydrodynamic structures in side of the highly nonlinear tidal bores and deepen the understanding of induced local scour and deposition. This project will also further contribute to the development of the theoretical model and numerical technique of SPH method, broaden its application field, show a new way for tidal bore simulation and provide scientific reference basis and technical supports for riverway planning and dike designing.

在潮差较大的喇叭形河口地区，涨潮过程中经常可以形成涌潮这一壮观的自然现象，其中以我国杭州湾地区的钱塘江涌潮最为著名。涌潮气势磅礴，是重要的自然和人文景观，但其蕴含的巨大能量严重威胁了沿岸群众和生产生活设施的安全。本项目拟基于一种无网格粒子法，即光滑粒子流体动力学（Smoothed Particle Hydrodynamics，SPH）方法，建立小尺度的涌潮-河床-结构物耦合数值模型，充分利用SPH方法在处理强非线性、大变形自由表面流以及多相流界面等方面的数值优势模拟涌潮潮头的运动演化过程，借助SPH方法的拉格朗日特性实现水沙二相的耦合模拟。本项目的研究有助于揭示强非线性涌潮潮头内部的水动力结构特征与河床冲淤动力机制，同时也为涌潮数值模拟研究提供新思路和新方法，进一步推进无网格数值方法在河口海岸水动力数值模拟中的应用，为河道规划、海塘设计等工作提供科学的参考依据和技术支撑。

在潮差较大的喇叭形河口地区，涨潮过程中经常可以形成涌潮这一壮观的自然现象，其中以我国杭州湾地区的钱塘江涌潮最为著名。涌潮气势磅礴，是重要的自然和人文景观，但其蕴含的巨大能量严重威胁了沿岸群众和生产生活设施的安全。本项目基于一种无网格粒子法，即光滑粒子流体动力学（Smoothed Particle Hydrodynamics，SPH）方法，结合SPH开边界技术，实现了小尺度涌潮的高精度模拟，探究了涌潮潮头的水动力结构特征，包括潮头波浪的翻卷及其触发的偶极子结构、紊流拟序结构的发育和演化规律、物质掺混和输运特征等。基于传统SPH水动力模型，通过引入泥沙浓度变量和土力学本构模型，提出了SPH框架下“悬移质-底沙”联合模拟的解决方案，揭示了不同含沙浓度水体的动力特征、以及不同状态下的泥沙在对流、扩散和沉降机制综合作用下的相互转化过程。运用水-沙-结构物耦合模型，模拟和研究了强漩滚涌潮和波浪卷破等强非线性水动力条件下泥沙的起动、输运和落淤特征。本项目的研究揭示了强非线性涌潮潮头内部的水动力结构特征与河床冲淤动力机制，同时也为涌潮数值模拟研究提供了新思路和新方法，进一步推进了无网格数值方法在河口海岸水动力数值模拟中的应用，为河道规划、海塘设计等工作提供了科学的参考依据和技术支撑。