大气边界层大涡模拟入口湍流生成方法研究

STUDY OF INFLOW TURBULENCE GENERATION METHODS WITH LARGE EDDY SIMULATION FOR ATMOSPHERIC BOUNDARY LAYER

  • 摘要: 生成满足大气边界层风场特性的入口湍流是开展结构风效应大涡模拟的关键问题之一。该文的主要目的是验证并探讨两类主要的大气边界层大涡模拟入口湍流生成方法的合理性与可行性。采用CDRFG(Consistent Discretizing Random Flow Generation)方法和被动模拟法生成大气边界层风场,从统计特性、流场结构和计算效率等方面进行对比分析,比较不同网格系统下的数值模拟结果,提出结构风效应大涡模拟的网格划分策略。结果表明:相比于CDRFG方法,被动模拟法生成的流场结构更加合理,但无法预先考虑脉动风场的空间相关性,且需要较高的计算成本和先验的流场信息。计算域的网格分辨率对于统计特性和流场结构的模拟精度具有重要影响,而目标区域的网格分辨率应依据控制工程结构风致响应的主要频带范围确定。

     

    Abstract: The generation of inflow turbulence with prescribed atmospheric boundary layer (ABL) flow characteristics is one of the key issues for the accurate evaluation of wind effects on structures using large-eddy simulation (LES). The main objective of this paper is to validate and discuss the rationality and feasibility of different inflow turbulence generation methods for ABL flows with LES. The CDRFG (Consistent Discretizing Random Flow Generation) method and passive simulation method are used to generate the ABL flows, and the comparative analysis is carried out from the aspects of statistical characteristics, flow field structures and computational efficiency. Based on the numerical simulation results under different mesh systems, the meshing scheme of LES for wind effects on engineering structures is proposed. The results show that the flow field structures generated by the passive simulation method is more reasonable than that of CDRFG method, but the spatial coherency of turbulent flow field cannot be taken into consideration in advance. It also requires large computational costs and prior knowledge of flow field. The grid resolution of computational domain is of great importance for the accurate simulation of statistical characteristics and ABL flows structures. However, the grid resolution in the neighboring region around target buildings should be chosen according to the dominant frequency band for the wind-induced responses of engineering structures.

     

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