Jet and Shock Wave from Collapse of Two Cavitation Bubbles

Abstract

As a common hydrodynamic phenomenon, multi-cavitation dynamics is widely found in many industries such as hydraulic engineering, shipping industry and chemical industry. The jet and shock wave phenomenon in the interaction of two cavitation bubbles are the basis of multi-cavitation bubbles interaction research. By respectively inducing two cavitation bubbles through laser and underwater low-voltage discharge, this paper tested the jet and shock wave resulting from the collapse of the two cavitation bubbles, and the following conclusions are obtained: (1) If the two cavitation bubbles are synchronously generated but in different size, as the distance between the two cavitation bubbles increases or the maximum radius of the smaller cavitation bubble increases, the effect of the small cavitation bubble on the larger one gradually changes from the surface wave phenomenon to jet that breaks through the larger bubble. When the two bubble center lines are parallel to the wall surface, this jet suppresses the formation of the jet to the wall surface when the large cavitation bubble collapses; if the two cavitation bubbles are generated at the same time with same size, as the initial distance of the two cavitation bubbles gradually decreases, the two bubbles are more likely to form a face-to-face collapse, and the smaller the distance between the two, the easier it is to fuse. (2) The impact of the initial moment of the cavitation bubble on the structure of the collapse shock wave is as follows: for two bubbles of different sizes formed synchronously, the shock wave propagates to the periphery in the form of a number of consecutive waves appearing in the larger bubble, while for the unsynchronized ones, shock waves appeared in both cavitation collapses, and a number of consecutive waves appear in the late-formed cavitation bubble. And multiple consecutive shock waves may overlap in some areas of the space. These conclusions have obvious implications for preventing cavitation damage and utilization of cavitation.

On the thermodynamic behaviors and interactions between bubble pairs: A numerical approach

“…Thus, it is important to investigate bubble interactions to reveal the cavitation mechanism. As the fundamental to study the interaction of multiple bubbles, the interaction between two cavitation bubbles is of great scientific value [25] . Tomita et al [26] demonstrated that the bubble-pair interaction was significantly affected by relative sizes and the mutual distance.…”

Study on Bubble Cavitation in Liquids for Bubbles Arranged in a Columnar Bubble Group

“…It has been pointed out that under a weak coupling effect between bubbles, bubbles maintain the shape of the hemisphere most of the time without contact and fusion, but, when the bubbles collapse, they form an interfacing jet [12]. We simulated the growth and collapse process of bubbles for five and seven bubbles set in a line using Fluent software with an initial radius of 30 µm and a distance of 200 µm between bubbles.…”

“…Moreover, there is a weak mutual coupling between the bubbles in a bubble group [9]. It is of a great significance to study the utilization of cavitation and coupling between multiple bubbles [10][11][12]. Nicolas Bremond et al [13] have investigated the dynamic behavior of cavitation bubbles on solid surfaces via experiments and numerical simulations.…”

“…The study of bubble dynamics is beneficial to regulating and controlling the intensity of ultrasonic cavitation. Ohl [16] and Luo Jing [12] have pointed out that the velocity of a bubble micro-jet is in the range 20~150 m/s. Tomita et al [17] have observed through high-speed photography that when small bubbles are near a wall, these small bubbles under the action of a shock wave directly hit the wall, which may cause a certain degree of denudation of the structure.…”

Collapse pressure measurement of single hollow glass microsphere using single-beam acoustic tweezer

“…To understand the mechanism of bubble collapse, models comprising a single bubble near a rigid wall are widely used because they can be used to specify the impacts of bubble size, population, and boundary effects in a well-defined setting [36] , [37] , [38] , [39] . Models involving multiple bubbles have also been used to observe changes in natural frequency and collapse pressure [40] , [41] , [42] , which are dependent on the interactions and void fractions between bubbles [43] , [44] , [45] , [46] . Such models must solve for more variables than single-bubble models and determine the collapse pressure based on the surrounding environment rather than the dynamics and structure of the bubble itself.…”