Bubble–particle critical detachment in isotropic turbulence: Role of particle hydrophobicity

To investigate the influence of particle hydrophobicity on bubble–particle critical detachment behavior in isotropic turbulence, an oscillating grid system approximating isotropic turbulence and a high-speed dynamic camera were utilized to record the changes in the circumference of the three-phase contact line and dynamic contact angle during the detachment process of three types of hydrophobic particles and bubbles at different oscillation frequencies. Based on the turbulent parameters extracted by numerical simulations, the results indicate that the flow field exhibits a sinusoidal periodic variation with grid motion. A highly isotropic turbulent environment is formed in the central region of the turbulent tank, and the velocity and vorticity of the flow field increase with the increase in oscillation frequency. Through the analysis of the bubble–particle detachment dynamics, it was found that particles of lower hydrophobicity tend to detach more easily with bubbles. Moreover, the detachment process can be divided into three sub-stages: bubble sliding, bubble shrinkage, and bubble necking rupture. Finally, based on experimental and numerical simulations, the critical flow field parameters for the bubble–particle detachment process under different hydrophobicity of particles were determined. This study provides a new method to determine the critical flow field parameters for detachment between bubbles and different hydrophobic particles.