圆管湍流近壁结构的DPIV实验研究

采用粒子数字图像测速(DPIV)对充分发展的圆管湍流进行了研究，测量结果和直接数值模拟结果的比较，表明作者开发的DPIV技术可取得满意的精度。在此基础上通过瞬时脉动速度场对圆管湍流的近壁结构进行了研究，并在近壁结构中检测出涡诱导的喷发和扫掠、低速条带和流向涡结构等拟序结构，而且发现低速条带和涡的诱导是低速流体喷发的必要条件。

Coherent structures in the near wall region of turbulent pipe flow

The digital particle image velocimetry (DPIV) technique is applied to study the flow structure of fully developed turbulent pipe flow. The measured results are in good agreement with those of direct numerical simulation. Based on the experimental data bank, the coherent structure in the near-wall region is studied according to the velocity fluctuation field. It is found that coherent structures exist in the near-wall region, such as ejection and sweeping induced by vortex, low speed streak and streamwise vortex, and the induction of vortex are the necessary condition for ejection.