Dynamic response of bubbles within a compliant tube

The dynamic response of bubbles in a liquid that are partially constrained by a surrounding tube or channel is important in a variety of fields, including diagnostic and therapeutic biomedical ultrasound and for microfluidic devices. In this study, numerical simulations, lumped parameter models, and experiments are used to investigate the effects of a surrounding tube on a bubble’s response to acoustic excitation. In particular, a coupled boundary element and finite element model and COMSOL MULTIPHYSICS models have been developed and used to investigate the nonlinear interactions of this three-phase system. Simulation results were compared to experimental measurements obtained using a scaled balloon model. The effects of tube parameters and bubble interactions on a bubble’s natural frequency important for proposed clinical applications of ultrasound are investigated. Resonance frequencies agree well with one-dimensional lumped parameter model predictions for a bubble well within a rigid tube, but deviate for a bubble near the tube end. Simulations also predict bubble translation along the tube axis and the aspherical oscillations and induced tube stresses at higher amplitudes. [Work supported by NIH and NSF CMMI.]