Global Mode Behavior of the Streamwise Velocity in Wakes

J. Wesfreid , S. Goujon-Durand , B. Zielinska

We characterize experimentally and numerically the two-dimensional structure of the global mode of the longitudinal component of the velocity in flow behind obstacles of different geometrical shapes. Measurements in a low velocity water tunnel and numerical simulations of the longitudinal component Vx of the oscillating velocity are carried out in the near wake region of the flow where vortex shedding is regular. We find that in the range of Reynolds numbers studied, the position (X max, Ymax) of the maximum of the global mode of Vx shift very little away from the central line in the y direction. The amplitude Amax of the maximum of the global mode scales as (R-Rc)1/2 in a range of R-Rc larger then in previous studies. We also confirm that Xmax of the global mode scales as (R-Rc)-1/2 in the same range of Reynolds numbers. An analysis of the initial slope of the global mode is presented. 


Domaines: Articles anciens

J. Wesfreid, S. Goujon-Durand, B. Zielinska. Global Mode Behavior of the Streamwise Velocity in Wakes. Journal de Physique II, 1996, 6 (10), pp.1343-1357. ⟨10.1051/jp2:1996135⟩. ⟨jpa-00248374⟩