Acoustic waveform of continuous bubbling in a non-Newtonian fluid.
We study experimentally the acoustic signal associated with a continuous bubble bursting at the free surface of a non-Newtonian fluid. Due to the fluid rheological properties, the bubble shape is elongated, and, when bursting at the free surface, acts as a resonator. For a given fluid concentration, at constant flow rate, repetitive bubble bursting occurs at the surface. We report a modulation pattern of the acoustic waveform through time. Moreover, we point out the existence of a precursor acoustic signal, recorded on the microphone array, previous to each bursting. The time delay between this precursor and the bursting signal is well correlated with the bursting signal frequency content. Their joint modulation through time is driven by the fluid rheology, which strongly depends on the presence of small satellite bubbles trapped in the fluid due to the yield stress.
Vidal
Valérie
V
Université de Lyon, Ecole Normale Supérieure, CNRS, 46 Allée d'Italie, Lyon Cedex 07, France. valerie.vidal@ens-lyon.fr
Ichihara
Mie
M
Ripepe
Maurizio
M
Kurita
Kei
K