波-流-植被耦合环境下射流Hybrid RANS/LES数值模拟研究

When wastewater is discharged into coastal zone or lakeshore, it often encounters currents, waves and vegetation. From the viewpoint of hydraulics, it can be generalized as the problem of jets in wave-current-vegetation environment. Using the advantages of large eddy simulation (LES) which has the ability of capturing the small eddy flow accurately, and Reynolds-Averaged Navier-Stokes equations (RANS) which have the merit of low computing cost, we will propose Hybrid RANS/LES mathematical model on the jets in wave-current-vegetation environment and develop the corresponding code in sigma coordinates. With the help of the mathematical model, we will study the mixing characteristics and mixing images on jets in wave-current-vegetation environment and the hydrodynamic factors affecting jets, jet turbulence etc. and then solve the problem of wastewater emission into coastal zone or lakeshore. The results will provide potential application in the planning of water environment for the wastewater discharged into the ocean. As a result, the research will be important theoretical and practical significance in the development of Hybrid RANS/LES.

针对以射流形式向海（江、湖）岸带排放的废污水常遇到的水流、波浪和植被等问题，利用能够准确捕捉流体精细流动的大涡模拟技术与无需付出昂贵计算代价的雷诺时均方法，建立能求解波-流-植被耦合环境下射流问题的hydrid RANS/LES数学模型，并开发出相应的程序。利用该研发的程序研究射流在波-流-植被耦合作用下的混合特性，给出射流掺混图像，并分析出影响射流的水动力以及植被分布密度等因素，从而总结这些因素对射流特征量相关性、湍动能和耗散率、速度高阶矩等湍流特性差异，进而探讨射流在波-流-植被环境下的排放规律和混合机理，为近海（江、湖）岸带废水排放的水环境规划提供理论依据和技术支撑。本研究具有重要的理论价值和现实意义，能够促进Hybrid RANS/LES数值模拟技术的发展和理论创新。

针对以射流形式废污水向海（江、湖）排放常遇到水流、波浪和植被等问题，利用能够准确捕捉流体精细流动的大涡模拟技术与无需付出昂贵计算代价的雷诺时均方法，建立波-流-植被环境下射流问题的hydrid RANS/LES数学模型，并开发相应的程序。. 本研究在前人的基础上，在有限差分的框架下构建了以射流形式的污染物在植被和水流环境中三维非定常湍流数值模拟理论和方法，采用先进刚柔型植被和水流相互作用的理论和方法，构建了相应的数学模型，并开发出Fortran语言程序，研究和预测污染物在植被和水流环境中扩散过程和机理。在构建了模型的同时，提出了湍流模型在植被环境中的修正方法以及采用提出的两阶段二阶精度非线性强稳定守恒Runge-Kutta 格式和分步算法耦合方法求解了控制方程。