Experimental study of a submerged fountain

¹ Laboratoire Ondes et Acoustique, ESPCI, Université Denis Diderot (URA CNRS 1503), 10 rue Vauquelin, 75231 Paris Cedex 05, France
² PMMH, Ecole Supérieure de Physique et Chimie Industrielles de Paris, (URA CNRS 857), 10 rue Vauquelin, 75231 Paris Cedex 05, France

Received: 11 April 1997
Accepted: 17 July 1997

Abstract

We present an experimental study of a vertical planar water jet impinging from below on a water/air interface. Varying the jet velocity and the cavity depth, three regimes are observed: at small velocities or high cavity depths, the jet is stable and the surface bump vertically above the jet is stationary. Increasing the velocity, the bump starts oscillating along the free surface at a well-defined frequency. This motion corresponds to the destabilization of the jet confined in the bulk of the cavity to a self-sustained oscillation regime, characteristic of the behavior of confined jets. Increasing further the velocity induces a transition to a behavior with more complex frequency spectrum. This paper presents a detailed study of the self-sustained oscillation regime. The frequency at the onset is studied as a function of the cavity depth and we show an unusual behavior of the frequency with the distance from the threshold.