Bubble Cloud Dynamics Research Articles

Dynamical Interactions in a Multi-Bubble Cloud

Results of studies on the dynamics of “clouds” of bubbles via both an analytical technique using asymptotic expansions, and via numerical simulation using a three-dimensional boundary element technique (BEM) are reported. The asymptotic method relies on the assumption that the characteristic bubble size is much smaller than the characteristic inter-bubble distance. Results obtained from the two methods are compared, and are found to agree in the domain of validity of the asymptotic technique, which is for very low void fractions. Next, results of several numerical experiments conducted using the BEM algorithm are reported. The results indicate the influence of the mutual interaction on the dynamics of multiple bubble clouds.

Existence theory and invariant manifolds of bubble clouds

This work is motivated by a desire to understand the dynamics of a cloud of bubbles in the wake of a ship. In particular we are interested in understanding how the sound waves from the propellors excite the cloud and how the cloud in turn modifies these waves. Many applications of bubble cloud dynamics exist ranging from cavitation damage to shock wave propagation in bubbly liquids

Linearized dynamics of spherical bubble clouds

The present work investigates the dynamics of the one-dimensional, unsteady flow of a spherical bubble cloud subject to harmonic far-field pressure excitation. Bubble dynamics effects and energy dissipation due to viscosity, heat transfer, liquid compressibility and relative motion of the two phases are included. The equations of motion for the average flow and the bubble radius are linearized and a closed-form solution is obtained. The results are then generalized by means of Fourier synthesis to the case of arbitrary far-field pressure excitation. The flow displays various regimes (sub-resonant, trans-resonant and super-resonant) with different properties depending on the value of the relevant flow parameters. Examples are discussed in order to show the effects of the inclusion of the various energy dissipation mechanisms. Finally the results for the case of Gaussian-shaped far-field pressure change are presented and the most important limitations of the theory are briefly discussed. The simple linearized dynamical analysis developed so far clearly demonstrates the importance of the complex phenomena connected to the interaction of the dynamics of the bubbles with the flow and provides an introduction to the more realistic study of the same flows with nonlinear bubble dynamics.