난류경계층내 주유동방향 와구조와 벽압력 변동간의 상관관계

Abstract

The relations between wall pressure fluctuations and near-wall streamwise vortices are investigated in a spatially-developing turbulent boundary layer using the direct numerical simulation. The power spectra and two-point correlations of wall pressure fluctuations are presented to validate the present simulation. Emphasis is placed on the identification of the correlation between wall pressure fluctuations and streamwise vorticities. It is shown that wall pressure fluctuations are directly linked with the upstream streamwise vortices in the buffer region of the turbulent boundary layer. The maximum correlation occurs with the spanwise displacement from the location of wall pressure fluctuations. The conditionally-averaged vorticity field and the quadrant analysis of Reynolds shear stress indicate that the sweep events due to streamwise vortices generate positive wall pressure fluctuations, while negative wall pressure fluctuations are created beneath the ejection events and vortex cores. The instantaneous flow field and time records reveal that the rise of high wall pressure fluctuations coincide with the passages of the upstream streamwise vortices.