Experimental scalar spectra in chaotic advection

International audienceWe investigate scalar spectra in a Hele-Shaw cell, where mixing is achieved through chaotic advection. Even though the flow is almost 2D (the dependance in z is parabolic velocity profile), we recover features found numerically in 3D chaotic advection, that are also similar with what one would expect in a turbulent flow: a −1.1 power-law behavior is found at intermediate scales, while the spectrum decays exponentially at the smallest scales at which diffusion is effective. Moreover, a scaling in P e −1/2 (therefore in Sc −1/2) is found, which is consistent with the scaling of the Batchelor scalar dissipation scale