近壁湍流相干结构演化规律、预测模型及在大涡模拟中的应用

The strong shear and anisotropy in the near-wall region complicated the flow physics of wall turbulence, and greatly hindered the development of prediction and control of wall-bounded turbulent flows. Coherent structures in the near-wall region play a key role in turbulence production and sustainment. In the present project, the systemetic studies will be carried on the evolution of near-wall coherent structures and their interaction with turbulence in the outer region based on the numerical experiments and theoretical analysis. The main concern will be focused on the influence of compressibility, roughness and particles. The predictive models will be developed for near-wall turbulence and applied to the near-wall treatment to enhance the efficiency and accuracy of large-eddy simulation of high-Reynolds number wall turbulence. The results will be verified by comparison with typical direct numerical simulation and experimental data.

壁湍流的近壁区存在强剪切和强各向异性，使得壁湍流的物理机理更加复杂，严重制约了壁湍流预测方法和控制策略的发展。近壁区的相干结构在壁湍流的产生和维持中起重要作用，并和高摩阻、高热流、高噪声的产生密切相关。本课题拟结合壁湍流的数值模拟实验和理论分析，系统开展近壁区湍流结构演化规律以及内外区影响机制的研究，重点关注压缩性、粗糙度和颗粒的影响，在此基础上，构建近壁区湍流脉动的预测模型，并与大涡模拟相结合，提出近壁区模拟的新方法，提高高雷诺数壁湍流大涡模拟的精度和效率。预测结果将采用典型的直接数值模拟和实验数据进行验证。

壁湍流的近壁区和高摩阻、高热流、高噪声的产生密切相关，是湍流预测和控制的关键区域，而近壁区复杂的物理机理严重制约了壁湍流预测方法和控制策略的发展。本项目通过对近壁区湍流结构演化规律以及内外区影响机制的研究，构建近壁区湍流脉动的预测模型，并与大涡模拟相结合，提出近壁区模拟的新方法，以提高壁湍流大涡模拟的精度和效率。本项目获得的重要结果有：(1) 构建了近壁区湍流速度、温度和标量脉动的预测模型；（2）发展了离面边界大涡模拟方法；（3）定量揭示了压缩性和壁温对壁湍流摩阻、压力脉动以及流动结构的影响；（4）揭示了湍流与波动表面的能量传输机制，提出了粗糙表面湍流能量和阻力的新标度；（5）揭示了湍流大尺度结构对颗粒输运和分布的影响规律与机理。通过本项目的研究，对复杂壁湍流的统计性质和流动结构有了新的认识，为大涡模拟的进一步应用提供了新的理论基础和技术途径。