Impulsive forces of two spark-generated cavity bubbles with phase differences

• Published in: Ultrasonics sonochemistry 2022-05, Vol.86, p.106042-106042, Article 106042
• Main Authors: Jung, Rho-Taek, Naing, Nyo Me Thet
• Format: Article
• Language: English
• Subjects: Impulsive forces; Phase differences; PVDF; Short Communication; Spark generation; Two-bubble interactions
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2022.106042

•In-phase and out-of-phase tandem bubbles are created by a spark-induced method near the vertical boundary.•Bubble shape evolutions and impact forces are analyzed by using a high-speed imaging system and PVDF film sensor.•Collapse time of single bubbles, in-phase pairs, and antiphase pairs are discussed.•Impulsive forces result from different inter bubble distances, and temporal separations are investigated. The characteristics of synchronous and phase difference bubble pairs in axisymmetric configuration near a boundary are investigated experimentally by the spark discharge method. Their destructive forces on nearby boundaries are measured using a polyvinylidene fluoride sensor. The bubble pair interactions and deformed features in the boundary vicinity are dissimilar to those in bulk water. Moreover, significant discrepancies between in-phase and out-of-phase pair interactions and their intensities of impulses are also witnessed. The interbubble distance (η), stand-off distance from the boundary (γ), and phase offset (τ) are crucial parameters affecting the shape evolutions and impulsive forces. From the qualitative analysis of sensor acquisition and high-speed imaging, it is observed that bubble periods are either prolonged or shorter than their corresponding isolated single cavity according to different parameters and arrangements. Additionally, the strongest impingements are produced by in-phase pairs. The impulses of phase difference bubble pairs are remarkably lower than in-phase pairs and even lower than a single bubble in some arrangements.