基于k-ε模型模拟平衡态大气边界层的比较研究

平衡态大气边界层的准确模拟是计算风工程领域的基础性难题，也是研究热点问题之一。该文首先对近年来国内外针对这一问题的理论研究成果按入流边界条件、湍流模型参数、附加源项模型以及壁面函数模型等四个方面进行了全面梳理和系统总结，并建议了一组新的标准k-ε模型湍流模型参数和通用壁面函数模型表达式。接着，采用计算流体动力学方法，建立简单边界层流动数值风洞模型，按照以上四种类别采用递进的方法对这些理论成果进行了详细的数值模拟验证和比较分析。结果表明：基于湍动能k方程解析解的入流边界条件并不必然会生成平衡态边界层，它和湍动能剖面的数学模型表达形式关系很大；除入流湍流边界条件外，湍流模型参数取值及壁面函数对平衡态大气边界层的模拟亦有较大影响，而增加源项并不能有效改善速度和湍动能剖面在整个流域范围的自保持性。该文对这一类问题的研究具有一定参考价值。

A COMPARATIVE STUDY ON THE SIMULATION OF NEUTRAL ATMOSPHERIC BOUNDARY LAYER BASED ON THE k-ε TURBULENCE MODEL

Accurately modeling the neutral equilibrium atmospheric boundary layers (ABL) is a fundamental problem in the field of computational wind engineering (CWE), which is a hot issue in recent years. This paper provides a comprehensive and systematical summary of the theoretical research advances on this topic in recent years from four aspects, that is, the inflow boundary conditions, the turbulence model parameters, the additional source and the wall function, respectively, and proposed a new set of model parameters and a general wall function based on the standard k-ε turbulence model. A numerical wind tunnel model was built to model a simple boundary layer flow by CFD (computational fluid dynamics) method according to the above four categories. Numerical results were compared and analyzed successively in details. It shows that the imposed inflow boundary conditions that were deduced from the analytical solution of the turbulent kinetic energy k equation do not necessarily generate the equilibrium ABL, which depends on the mathematical model of the k profile to a large extent. Apart from the inflow boundary conditions, the turbulence model parameters and the wall function also had a great effect on modelling the neutral equilibrium ABL. Adding source terms in the turbulence model equations cannot effectively improve the self-maintenance of the velocity and the turbulent kinetic energy profiles throughout the whole domain without any obstacles. The above conclusions would be helpful for the research on this topic.