Vendredi 19 octobre 2012 à 11h, dans l'amphi du centre de l'Yvette : " Waves on a foam surface: propagation of subshear and supershear pulses." par Guillaume Lagubeau, Física No Lineal, USACH, Santiago, Chile.
Résumé
Liquid foams consist in a concentrated dispersion of gas bubbles in a continuous liquid phase. The dynamical properties of such a mixture, studied by rheologists over the last 30 years, are now well characterized, although not fully understood. Acoustics as a way to probe foam fast dynamics is a developing tool, that has to face the challenge of the strong dissipation occurring in this medium and therefore requires highly accurate measurement methods.
Taking advantage of the precision of a space-time resolved profilometry technique we present here the first foam study using surface acoustics. Subsequently, we observe two kinds of surfaces waves: the well known anelastic Rayleigh wave and a supershear surface wave that can be identified with another solution of Rayleigh’s secular equation.