Wall pressure and conditional flow structures downstream of a reattaching flow region

The separating and reattaching flow over a thick plate with sharp angle at Re = 80,000 is investigated using pressure and HS-PIV measurements. After having studied the mean flow properties, which are found in good agreement with the literature, a particular emphasis is given concerning the eduction and the analysis of the evolution of the large scale vortices downstream of the reattachment. This is done using an adapted multi-time and multichannel stochastic estimation of the velocity correlated with the fluctuating wall pressure. Swirling strength and Finite Time Lyapunov Exponents are then used in order to detect and characterize the structures and their dynamics. Conditional statistics based on the feature longitudinal position are computed in order to educe intensity, size, position and convection velocity of each conditional feature. A rapid longitudinal decrease of the fluctuating kinetic energy carried by these conditional structures has been observed, highlighting their rapid loss of coherence downstream mean reattachment.

► Investigation of the separating and reattaching flow over a thick plate.
► Analysis of the evolution of the large scale vortices downstream of the reattachment.
► Stochastic estimation of the velocity correlated with the fluctuating wall pressure.
► Use of swirling strength and FTLE to detect and characterize the coherent structures.
► Observation of a rapid loss of coherence of vortices downstream of the reattachment.