近壁湍流的降阶模型及应用

由条带和流向涡的循环再生构成的近壁自维持过程(self-sustaining process, SSP)是壁湍流产生和维持的重要机制. 文章通过对最小槽道的直接数值模拟(direct numerical simulation, DNS)获得近壁自维持过程的流场数据, 采用正规正交分解法(proper orthogonal decomposition, POD)对该数据进行分析, 获得了不同流向和展向尺度的特征模态, 通过将Navier-Stokes方程在这些模态上进行投影, 得到近壁自维持过程的降阶模型, 并采用DNS数据对降阶模型的预测能力进行了评价. 该模型被初步应用于大涡模拟近壁模型的构造. 

Reduced-Order Model for Near-Wall Turbulence and Its Application

The self-sustaining process (SSP) consisting of streaks and streamwise vortices in the near-wall region is an important mechanism for the generation and maintenance of wall-bounded turbulence. In the present study, the flow field of near-wall SSP was obtained by direct numerical simulation of the minimal flow unit and analyzed by using proper orthogonal decomposition(POD). POD modes on different streamwise and spanwise scales were obtained and the reduced-order model (ROM) of SSP was derived by projecting the Navier-Stokes equations on these modes. The prediction ability of the ROM was validated by DNS data. The ROM has been preliminarily applied on the construction of the wall models for large eddy simulation.