QUANTITATIVE EXPERIMENTAL-STUDY OF THE FREE DECAY OF QUASI-2-DIMENSIONAL TURBULENCE

A quantitative experimental study of freely decaying quasi-two-dimensional turbulence is presented. The flow is produced in a thin layer of electrolyte by using a steady, spatially periodic, electromagnetic forcing. The particle-image-velocimetry method is used to determine the instantaneous velocity field, the vorticity field, and the stream function. Global quantities, such as the energy, the enstrophy, and the kurtosis of the vorticity distribution are measured, and geometrical properties, such as the number of eddies, their size, and their mean separation, are determined. Unexpected characteristics are obtained, revealing the existence of a new form of quasi-two-dimensional turbulence, which we call liquid.