后向台阶尾部流场高分辨层析PIV数据集中的流动结构辨识

The flow behind a backward facing step of 6 mm in height has been investigated by means of highresolution
tomographic PIV. The shedding of vortices was stabilized by acoustic excitation, enab领 phaselocked
measurements of the flow field in a volume of 70x95x7 mm3. The gathered vector volumes with a
vector spacing of approx. 0.25 mm in each direction were investigated by the method of conditional
averaging. Basic flow structures, related to Q2 and Q4-events were extracted and their development in time
was characterized, using methods of joint probability density functions of the fluctuations and of the
invariants of the velocity gradient tensor. 自适应粒子成像测速场仪（PIV） 德国LaVision PIV/PLIF粒子成像测速场仪 体视层析粒子成像测速系统(Tomo-PIV)