Hysteresis of inertial cavitation activity induced by fluctuating bubble size distribution

Abstract

Amongst the variety of complex phenomena encountered in nonlinear physics, a hysteretic effect can be expected on ultrasound cavitation due to the intrinsic nonlinearity of bubble dynamics. When applying successive ultrasound shots for increasing and decreasing acoustic intensities, a hysteretic behaviour is experimentally observed on inertial cavitation activity, with a loop area sensitive to the inertial cavitation threshold. To get a better insight of the phenomena underlying this hysteretic effect, the evolution of the bubble size distribution is studied numerically by implementing rectified diffusion, fragmentation process, rising and dissolution of bubbles from an initial bubble size distribution. When applying increasing and decreasing acoustic intensities, the numerical distribution exhibits asymmetry in bubble number and distribution. The resulting inertial cavitation activity is assessed through the numerical broadband noise of the emitted acoustic radiation of the bubble cloud dynamics. This approach allows obtaining qualitatively the observed hysteretic effect and its interest in terms of control is discussed.

Nanomaterial-based sonosensitizers: from exemplary design towards purposeful improvement

“…Stimulated by US, the gas in the liquid oscillates with the compression and decompression cycle, and triggers microfluidic and radiation forces. 17 It interferes with the adjacent cell surface and cell membrane, thereby increasing the penetration and diffusion of drugs. Regardless of the type, the eventual result favors drug delivery into the cell.…”