Cavitation nuclei regeneration – CANURE

The appearance of bubbles in a liquid induced by pressure decreases, i.e. cavitation, occurs in a wide range of applications. In some fields such as naval propulsion or hydraulic systems, cavitation is detrimental and needs to be avoided. On the other hand, cavitation can also be used in medicine (ultrasound therapy), in sonochemistry or in wastewater treatment. In all of these applications, cavitation is heterogeneous and arises from micro/nanobubbles, called cavitation nuclei, stabilized by surface defects of impurities or walls. Nuclei population of a solution remains unknown and the cavitation still limits further developments of the different applications.
Recent studies have shown that nuclei can be deactivated by using acoustic pulses paving the way toward a potentiel control of the cavitation. However, this deactivation does not last and a spontaneous regeneration of nuclei has been observed.
In this project we propose to elucidate this newly discovered phenomena of nuclei reformation to, in the end, develop innovatives strategies to control the cavitation based on this regeneration. To this aim, an original experimental setup able to monitor nuclei at the microscopic scale will be developed and used to measure nuclei reformation. Defect properties (shape and hydrophobicity) and the dissolved gas content will play a key role in the nuclei regeneration. These parameters will be first studied at the scale of a single defect. Collective behavior as well as competition with chemical impurities will be investigated a second time. The fundamental understanding acquired during these studies will then be used to elaborate innovative strategies to control the cavitation.