论文标题
壁湍流中动量通量波动：超出墙壁的公式
Momentum flux fluctuations in wall turbulence: a formula beyond the law of the wall
论文作者
论文摘要
在壁湍流中，有一个子层，其中流向动量的平均壁正常通量是恒定的，并且与平均流向速度的对数壁正态谱有关。这种关系，即壁的定律，已用于估计壁表面的平均应力。但是，动量通量显示出较大的时间波动。为了将它们与墙壁相同位置处的流向速度的相关性联系起来，我们考虑了在流向和壁正常速度平面上波动的正交分解。由于预计会占主导动量通量的组件的较大时间尺度，因此它会通过暂时平滑来挑选。所得公式与风隧道中边界层的时间序列数据一致。我们还将公式扩展到热分层的情况。
Within wall turbulence, there is a sublayer where the mean wall-normal flux of the streamwise momentum is constant and related to the logarithmic wall-normal profile of the mean streamwise velocity. This relation, i.e., the law of the wall, has been used to estimate the mean stress at the wall surface. However, the momentum flux exhibits large temporal fluctuations. To relate them theoretically to those of the streamwise velocity at the same position from the wall, we consider an orthogonal decomposition of the fluctuations on a plane of the streamwise and wall-normal velocities. Since a large timescale is expected for the component that would dominate the momentum flux, it is singled out by temporal smoothing. The resultant formula is consistent with time-series data of a boundary layer in a wind tunnel. We also extend the formula to thermally stratified cases.
