Abstract
The flow field through an axisymmetric sudden expansion is measured using two multi-point LDV systems and an azimuthal structure is discussed by correlation of a fluctuation of velocity profile and conditional average, especially make attention to the behavior near wall region. The raw spatio-temporal velocity field between two measuring lines with some azimuthal angle shows a complex one. The contour map of correlation in azimuthal direction - lag time field indicates staggered like structure. The conditional average shows the structure of reattachment phenomenon.
