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Pressure waves propagating through bubble-containing liquids in tubes experience considerable attenuation. Researchers at University of Tsukuba have derived an equation describing this phenomenon, demonstrating that beyond liquid viscosity and compressibility, variations in tube cross-sectional area contribute to wave attenuation. Their analysis reveals that the rate of change in tube cross-sectional area represents a critical parameter governing pressure wave attenuation in such systems.

Tsukuba, Japan—Pressure waves propagating through bubble-containing liquids in tubes, known as "bubbly flow," behave distinctly from those in single-phase liquids, necessitating precise understanding and control of their propagation processes. Pressure wave attenuation is particularly crucial in characterizing these propagation dynamics, requiring clear identification of attenuation factors and mechanisms. Although pressure waves in bubbly flows are known to be highly sensitive to changes in tube cross-sectional area, the underlying attenuation mechanism has remained unresolved.

In this study, researchers at University of Tsukuba developed an equation describing pressure wave propagation in bubbly flows through tubes with varying cross-sectional areas. Their analysis confirmed that changes in tube cross-sectional area contributes to pressure wave attenuation in bubbly flows. Quantitative comparisons with other attenuation factors, including liquid phase viscosity and compressibility, revealed that the rate of change in tube cross-sectional area is a key parameter governing pressure wave attenuation.

This research advances the fundamental understanding of pressure wave attenuation in bubbly flows. In addition, because the equation accommodates tubes of arbitrary cross-sectional shapes, it has promising applications in bubble generation utilizing converging-diverging tubes with abrupt cross-sectional area variations.

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This work was partly carried out with the aid of JSPS KAKENHI (No. 22K03898), the JKA and its promotion funds from KEIRIN RACE, and the Komiya Research Grant from the Turbomachinery Society of Japan. This work was partly based on results obtained from a project subsidized by the New Energy and Industrial Technology Development Organization (NEDO) (No. JPNP20004). This work was partly supported by the Top Runners in Strategy of Transborder Advan Researches (TRiSTAR) program conducted as the Strategic Professional Development Program for Young Researchers by the MEXT.

Original Paper

Title of original paper:

Elucidation of pressure wave attenuation due to cross-sectional area change in bubbly flow

Journal:

International Journal of Multiphase Flow

DOI:

10.1016/j.ijmultiphaseflow.2025.105138

Correspondence

Associate Professor KANAGAWA Tetsuya
Institute of Systems and Information Engineering, University of Tsukuba

Related Link

Institute of Systems and Information Engineering