Study on the interaction of vertically structured double cavitation bubbles induced by pulsed laser

Currently, the majority of research on double cavitation bubbles focuses on horizontally arranged structures, while investigations into the pulsation of vertically aligned double bubbles remain limited. This paper aims to conduct high-speed photography research on the interaction of vertically structured double cavitation bubbles induced by pulsed laser. The pulsed laser induced cavitation method is used to induce the formation of vertically arranged double cavitation bubbles, and high-speed photography techniques are employed to investigate their pulsation characteristics.The double cavitation bubbles studied are divided into three forms according to the initial size ratio S*. The results indicate that, for vertically arranged double cavitation bubbles, similar-sized bubbles \(\left( {1 \le S^\ast < 1.15} \right)\) $\left(1\le S^{*}<1.15\right)$ exhibit mutual attraction and fusion, with a tendency for fusion preceding separation. Bubbles of different sizes \(\left( {1.15 \le S^\ast < 3} \right)\) $\left(1.15\le S^{*}<3\right)$ repel during the expansion process and attract during the shrinkage process.The pulsation of small bubbles with extremely different sizes \(\left( {S^\ast \ge 3} \right)\) $\left(S^{*}\ge 3\right)$ is strongly influenced by repulsion, while the pulsation of large bubbles is essentially unaffected.