What We Learned from Cavitation Bubbles in Microgravity

Abstract

The present chapter is about the Flash and Splash project, which is dedicated to the study of bubble dynamics in microgravity. The story of this project started in 2004 with a simple curiosity on how a cavitation bubble may behave within a water drop and evolved into an outstanding, internationally renowned science project as well as a wonderful human adventure. So far, we have participated in nine European Space Agency (ESA) parabolic flight campaigns (PFC) and made a significant progress in understanding the cavitation phenomenon. First, we investigated the dynamics of a cavitation bubble within a water drop and learned how the collapse may lead to the formation of a double jet. We discovered the formation of secondary cavitation due to the confinement of shockwaves within the drop. We used this result to propose a new path for erosion due to a high-speed impact of water drops on a solid surface. Then, we addressed the effect of gravity on bubble dynamics and came up with a unified framework to explain and predict key phenomena, such as microjets, shockwaves and luminescence. Parabolic flights gave us the unique opportunity to modulate the gravity-induced pressure gradient, which is crucial for the fate of a collapsing bubble.

Research on Eccentric Cavitation Bubble Collapse Dynamics within Droplets

“…The collapse process of bubbles in confined domains is affected by the boundary, resulting in a complex dynamics of bubble collapse [11]. Cavitation within the droplet will increase the degree of droplet atomization [12], causing violent droplet splash [13] and further explosions [14]. In addition, a cavitation bubble within a droplet is also of interest in many other fields [15][16][17][18], e.g., ultrasonic material cleaning [19] and inkjet printing [20].…”

A Review of the Dynamics Progress of Bubble Collapse within Droplet and Droplet Splash

“…For example, the theoretical model suitable for the dynamics of cavitation bubble collapse within droplets still suffers many limitations. Based on these, the topic of cavitation bubbles within droplets is being given increasing attention by researchers [56].…”