Bubble dynamics for broadband microrheology of complex fluids

Tuning local microstructure of colloidal gels by ultrasound-activated deformable inclusions

“…We propose to extend the applicability of ultrasound manipulation of complex fluids by embedding deformable inclusions that can be activated by ultrasound, namely gas bubbles. Gas bubbles can undergo deformation by passive dissolution due to gas diffusion, and can be actively driven into volumetric oscillations under ultrasound excitation 26 . These oscillations have already been shown to drive dynamic self-assembly in colloid monolayers on the surface of bubbles 27 , and to destroy such monolayers for large-amplitude forcing 28 .…”

“…This field is prescribed by the no-penetration condition at the bubble surface and the incompressibility of the surrounding medium, leading to v = ṘR 2 /r 2 e r for spherical bubbles. This velocity field produces a purely extensional strain field decaying like r −3 away from the bubble 26 . Bubbles then completely prescribe how the constituents of the surrounding medium are strained, as long as it behaves as a homogeneous medium.…”

“…Dimensionless groups based on the yield stress of the colloidal gel, σ Y , provide information on whether the surrounding medium behaves predominantly as an elastic solid or a viscous fluid. The plasto-capillary number Pl examines whether the yield stress is large enough to arrest bubble dissolution 26 . The value for our system is:…”

Ultrasound-induced nonlinear oscillations of a spherical bubble in a gelatin gel

“…After returning to room temperature, the gel is supersaturated with dissolved air (Hamaguchi & Ando 2015) since mass diffusion is much slower than heat diffusion. While viscoelastic properties of gels under strain rates up to approximately 100 Hz are measured commonly by commercial rheometers, those of the gel deformed under ultrasound irradiation cannot be measured in the same manner (Kwon & Subhash 2010; Jamburidze et al 2017; Saint-Michel & Garbin 2020) and thus need to be treated as unknown parameters in this study.…”

Effect of cavitation bubble on the dispersion of magnetorheological polishing fluid under ultrasonic preparation

“…Afterward, lots of new models were provided by modifying the Rayleigh-Plesset equation, such as the Keller-Miksis model [11] and Gilmore model [12] considering the liquid compressibility, Flynn model [13] considering the thermodynamic characteristics of the gas inside the bubble, and others. In recent years, some scholars have begun to focus on the application of the bubble dynamics model in suspension, such as visco-elastic fluids [14] , complex rheology fluids [15] , and grinding fluid [16] . However, the present cavitation bubble model is mainly suitable for water solution or the liquid approximated as a water solution.…”