MIXING IN HORIZONTALLY HETEROGENEOUS FLOWS

An experimental study of mixing across density interfaces produced by laterally heterogeneous turbulence is presented in this paper. The tur bulence is generated by a flow or air bubles rising through a density interface produced by brine and fresh water. The mixing efficiency, et a, of the process is measured comparing the increase in potential ener gy with the available kinetic energy. We find that there is a decrease in the global mixing efficiency of the process with the length of the tank, the shape of eta(Ri) depends also on the air flow producing the turbulence, showing a geometrical limit to the ammount of kinetic ene rgy which may be used for mixing.