Hysteresis in cavitation emissions during a ramped-then-deramped amplitude sonication: A theoretical and experimental investigation.

Dynamic hysteresis in cavitation emissions is investigated experimentally and numerically using a continuous ramped-then-deramped acoustic excitation. Hydrophone spectrograms reveal clear asymmetries between the ramped and deramped phases at identical excitation amplitudes, including differences in harmonic, subharmonic, and broadband components. These observations show that the acoustic state of the bubble population depends on the excitation history. A fully coupled 12-bubble model, incorporating spatially resolved interaction forces, reproduces all salient experimental features, including the subharmonic route to chaos, broadband emission, and broadband clearing. Poincaré mapping and continuation analysis reveal multiple coexisting attractors, distinguished by oscillation amplitude and period, delimited by saddle-node and period-doubling bifurcations. The hysteresis observed under continuous excitation arises from history-dependent convergence to these attractors. Basin-of-attraction computations demonstrate that attractor selection depends jointly on initial conditions and bubble-bubble interaction, enabling different bubbles to converge to distinct attractors under identical excitation amplitudes. Together, these results establish a physically interpretable nonlinear-dynamical mechanism underlying hysteresis in cavitation emission. Supplementary Information: The online version contains supplementary material available at 10.1007/s11071-026-12462-3.