Coupled FEM and BEM code for simulating acoustically excited bubbles near deformable structures

Abstract

An understanding of biotissue-bubble interactions and the stresses induced in the tissue is needed to identify potential mechanisms of tissue damage, such as vessel rupture, by acoustically excited bubbles. Interactions between acoustically excited bubbles and nearby rigid structures have been studied effectively using the boundary element method. However, if the nearby structure is a biotissue, structure deformations will affect the bubble response. In this paper a coupled finite element and boundary element code, developed to investigate the interactions between an acoustically excited bubble and a deformable structure, is presented. In particular, this model was developed to investigate the response of bubbles within deformable tubes. This code is validated by comparison to other simulation and experimental results and employed to obtain the response of an acoustically excited bubble centered within a tube. General characteristics of bubble-tube interactions and stresses induced in the tube wall are described by considering typical simulation results.

Temperature change near microbubbles within a capillary network during focused ultrasound

“…Any method that can calculate the radius as a function of time of an oscillating bubble can be input. Particularly, a method that accounts for the elasticity of the vessel wall, such as that of Miao and Gracewski[13] may be more appropriate. The current models of bubbles within tubes (e.g.…”

Interaction between microbubble and elastic microvessel in low frequency ultrasound field using finite element method

“…Previous studies focused on comparing the circumferential stress to the tensile strength of the vessel wall to predict the damage threshold. Under ultrasound excitation with PNP 0.2 MPa and center frequency 1 MHz, the maximum hoop stress exceeded 1.5 MPa assuming the vessel wall elasticity 5 MPa [11,12]. However, it is possible that the rapid compression stress during bubble collapse plays important role in the microvessel wall in ultrasound field.…”

“…The mechanical property of the vessel wall was assumed to be linear elastic material in most studies [10][11][12]. However, Fung's experimental study showed that the stressstrain relationship was nonlinear when a torsion test was made on the mesentery.…”

“…The stress distribution could not be analyzed. Coupled finite element and boundary element code was developed to simulate the acoustic response of microbubble in a deformable vessel, but it has limitation by assuming the fluid inviscid and vessel wall linear elastic [11,12].…”

Interactions between two oscillating bubbles in a rigid tube

“…Their simulation went on after the jets contacted, which showed that a toroidal bubble formed at the end of the collapse, afterwards a ring-shaped jet was generated pointing towards the tube wall. On the bubble collapse in an elastic tube, a coupled FEM and BEM code for simulation was developed by Miao [14], describing the typical bubble-tube interactions and stresses. Coralic [15] studied shock-induced collapse of a bubble inside a deformable vessel, whose results showed that a 40 MPa shockwave to collapse the bubble generated a vessel wall pressure of almost 450 MPa, inducing an invagination of nearly 50% of the initial vessel radius on a 10 ns timescale.…”