Turbulence structure in the immediate vicinity of the shear-free air-waterinterface induced by a deeply submerged jet

A PIV based technique is developed to perform flow measurements in the vici nity of the air-water interface of a submerged confined jet. Both the inter face movement and the velocity field immediately beneath it are measured si multaneously. A detailed turbulence structure in the surface influence regi on is thus obtained. Flow parameters evaluated without and w.r.t. the inter face are quantified and compared against previous works obtained using the conventional Eulerian-based instrumentation which do not account for the in terface fluctuation, and checked against analytical model characterising th e turbulence close to a assumed flat air-water interface.