多分散気泡流の気泡相互作用(PoF・佐久間)

佐久間敬佑（現M1、旧B4）の論文が、Physics of Fluids (top 10%ジャーナル, JCR 2024, JIF percentile: 92.7% (Physics, Fluids & Plasmas), IF: 4.3) から出版されました。

Sakuma, K., Hemmi, K. and Kanagawa, T., “Bubble–bubble interaction governs nonlinear acoustic waves in polydisperse bubbly liquids,” Physics of Fluids, Vol.~38 (2026.3), 033345.

気泡を多数含む液体中を伝わる弱非線形圧力波について、現実に即した「気泡サイズがばらばらな（多分散な）気泡群」を対象とし、気泡同士の相互作用を組み込んだ非線形波動方程式（KdV–Burgers方程式）を理論的に導出しました。その結果、気泡同士の相互作用と気泡サイズのばらつき（多分散性）の両者が、波の非線形性・散逸・分散の3つの特性を相乗的に強めること、とりわけ波をばらけさせる分散効果が顕著に増大することが明らかになりました。これは波形がソリトン化する方向に非線形発展する傾向を示唆するものであり、超音波洗浄や超音波造影剤・超音波治療といった応用に向けた、気泡を含む媒質中の波動伝播を予測するための基礎理論として位置づけられます。

A paper by Keisuke Sakuma (currently M1) has been published in Physics of Fluids (a top 10% journal; JCR 2024, JIF percentile: 92.7% in Physics, Fluids & Plasmas; IF: 4.3).

Sakuma, K., Hemmi, K. and Kanagawa, T., “Bubble–bubble interaction governs nonlinear acoustic waves in polydisperse bubbly liquids,” Physics of Fluids, Vol.~38 (2026.3), 033345.

This study theoretically investigates the weakly nonlinear propagation of pressure waves in liquids containing many gas bubbles, focusing on the more realistic situation in which the bubbles possess a distribution of initial sizes (polydispersity). By incorporating bubble–bubble interactions, a nonlinear wave equation of the Korteweg–de Vries–Burgers type was derived for polydisperse bubbly liquids. The analysis reveals that bubble–bubble interactions and polydispersity synergistically enhance the nonlinear, dissipation, and dispersion characteristics of the propagating waves, with the dispersion effect in particular exhibiting a markedly large enhancement. These findings suggest a tendency toward soliton formation in the waveform evolution and provide a theoretical foundation for predicting wave propagation in bubble-laden media, with implications for applications including ultrasonic cleaning, ultrasound contrast agents, and therapeutic ultrasound.