Bidirectional seiching in a rectangular, open channel, lateral cavity

International audienceThe present work is dedicated to the free-surface oscillation of lateral cavities, i.e. horizontal cavities with free surface connected along one of their sides to a steady main flow. This oscillation phenomenon, named seiching, is studied experimentally, first for a square cavity and then for a rectangular one. Water surface oscillations are recorded and, for the square cavity, two standing waves of perpendicular axes appear to co-exist and are reconstructed individually using usual signal processing tools. Moreover, the corresponding oscillation frequencies appear to be well correlated with the peak frequencies of the velocity spectrum in the mixing layer. Finally, for the rectangular cavity, the standing wave of axis perpendicular to the mainstream axis disappears and an additional standing wave of streamwise axis appears