A sound wave travelling in water is scattered by a periodic assembly of air bubbles. The local structure matters even the low frequency regime. If bubbles are arranged face-centered cubic (fcc) lattice, total band gap opens near Minnaert resonance frequency. they diamond structure, which one obtains simply adding second bubble to unit cell, finds an additional branch with negative slope (optica...

Parallel asynchronous iterative algorithms exhibit features that are extremely well–suited for Grid computing, such as lack of synchronisation points. Unfortunately, they also suffer from slow convergence rates. In this paper we propose using asynchronous methods as a coarse–grain preconditioner in a flexible iterative method, where the preconditioner is allowed to change in each iteration step...

We study the influence of bubble-bubble interactions on the propagation of linear acoustic waves in bubbly liquids. Using the full model proposed by Fuster and Colonius [J. Fluid Mech. 688, 253 (2011)], numerical simulations reveal that direct bubble-bubble interactions have an appreciable effect for frequencies above the natural resonance frequency of the average size bubble. Based on the new ...

In turbulent Taylor-Couette flow, the injection of bubbles reduces the overall drag. On the other hand, rough walls enhance the overall drag. In this work, we inject bubbles into turbulent Taylor-Couette flow with rough walls (with a Reynolds number up to 4 x 10(5), finding an enhancement of the dimensionless drag as compared to the case without bubbles. The dimensional drag is unchanged. As in...

High-speed images of bubbly flow coupled with simultaneous passive acoustic measurements were carried out in a bubble column staged with structured fibrous catalysts. Local observations made with a high-speed camera system allow a detailed understanding of the influence of fabric structure on bubble formation processes and the determination of the Sauter bubble diameter. With acoustic measureme...