NEW VISUALIZATION METHODS AND SELF-SIMILAR ANALYSIS IN EXPERIMENTAL TURBULENCE STUDIES

Abstract. We present results on several laboratory experiments where a sharp density interface generated by either salt concentration or heat, advances due to grid stirred turbulence or to buoyancy. The fractal and multi-fractal measures will be used as a function of the position and time of the advance of the mixing fronts as topological indicators of the multi-scale of these complex flows. There are usually several fractal dimensions for the different physical indicators that may be related to different cascade types in a non-local non-equilibrium turbulent flow. The relationships between the spectra in a turbulent equilibrium cascade and the maximum value of the fractal dimension of a certain set of measurements of a fixed value are related and applied to several self similar situations. We discuss the advances in experimental techniques in the study of turbulence. Different types of visualization techniques and measurement techniques used in laboratory experiments are able to extract information about the intermittency and the self-similarity of the turbulence