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

On wall pressure fluctuations and their coupling with vortex dynamics in a separated–reattached turbulent flow over a blunt flat plate

“…Numerical approximations are described in Section 2 and the numerical ingredients, including the definition of the computational domain, boundary conditions, and grid generation, are presented in Section 3 . In Section 4 , we then validate our numerical results by comparisons with experimental measurements, coming from both the Pprime laboratory and different experiments ( Cherry et al, 1984;Kiya and Sasaki, 1985;Sicot et al, 2012;Tafti and Vanka, 1991 ). Thus, spectral, POD and EPOD (extended POD) analyses are applied on the present numerical data to determine the salient features of the pressure and velocity fields.…”

“…In the past, this configuration has widely been studied experimentally. Numerous experimental results are available in the literature on the structure of turbulent flow separation bubbles and its relaxation after the reattachment ( Castro and Epik, 1998;Castro and Haque, 1987;Cherry et al, 1984;Eaton and Johnston, 1981;Hoarau et al, 2006;Kiya and Sasaki, 1983;1985;Sicot et al, 2012 ). The dynamics of the separation bubble and its reattachment have mainly been reviewed on both the flow along a side of a blunt flat plate and the backward-facing step flow field.…”

“…The connection between these main mechanisms is still not clear and deserves more results for further analysis. The three-dimensional feature of large-scale structures in the reattaching zone was underlined and its influence on the wall pressure fluctuations was studied through either crosscorrelations ( Kiya and Sasaki, 1983;Saathoff and Melbourne, 1997 ) or extended POD analysis ( Hoarau et al, 2006;Sicot et al, 2012;Tran, 2012 ). Wall pressure fluctuations are related to the motion of large-scale vortices, especially hairpin vortices in the reattachment region that produce large amplitude fluctuations.…”

“…Experimental analysis also investigated the relaxation occurring downstream the reattachment. Although some characteristics (log-law for instance) of canonical boundary layers are re-established rather rapidly, the energetic mixing-layer like structures occurring around reattachment evolve very slowly since 70 boundary layer thicknesses are needed to recover common structures of a standard boundary layer ( Castro and Epik, 1996;1998;Sicot et al, 2012 ). Following these results, authors ( Castro and Epik, 1996;1998 ) conjectured that second order Reynolds stress models are not able to predict the slow decay of the energetic large scale structures in the outer part of the flow and its influence on the inner region.…”

A reduced order model based on Kalman filtering for sequential data assimilation of turbulent flows

“…The case of the flow around a thick plate of height H p is investigated combining DDES numerical simulation [44] (model ) and PIV experimental data [45] (observation). For the Reynolds number Re = 80000 here investigated, the flow exhibits full turbulent features.…”