Effects of Nuclei Size Distribution on The Dynamics of A Spherical Cloud of Cavitation Bubbles  

Oleh:

Wang, Yi-Chun

Jenis: Article from Bulletin/Magazine
Dalam koleksi: Journal of Fluids Engineering vol. 121 no. 4 (1999), page 881-886.
Topik: bubbles; nuciel size; distribution; spherical cloud; cavitation bubbles

Ketersediaan

Perpustakaan Pusat (Semanggi) Nomor Panggil: JJ89.1 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

The nonlinear dynamics of a spherical bubble cloud with nuclei size distribution are studied numerically. The spectrum of nuclei is assumed uniform initially. The simulations employ a non linear continuum bubbly mixture model with consideration of the presence of bubbles of different sizes. This model is then coupled with the Rayleigh - Plesset equation for the dynamics of bubbles. A numerical method based on the integral representation of the mixture continuity and momentum equations in the Lagrangian coordinates is developed to solve this set of integro - differential equations. Computational results show that the nuclei size distribution has significant effects on the cloud dynamics in comparison to the results for a single bubble size. One important effect is that the bubble collapse is always initiated near the surface of the cloud, even if the cloud has a very small initial void fraction. This effect has an important consequence, namely that the geometric focusing of the bubbly shock wave is always a part of the nonlinear dynamics associated with the collapse of a spherical cloud with nuclei size distribution. The strength of the shock and the oscillation structure behind the shock front are suppressed due to the effects of multiple bubble sizes. Far - field acoustic pressures radiated by two bubble clouds, one of equal - size bubbles and the other with bubble size distribution, are also compared. It is found that the cloud containing bubbles of different sizes emits a larger noise than the cloud of identical bubbles. Explanations for this effect are also presented.

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