Author(s)

A. V. Teterev, N. I. Misychenko, L. V. Rudak & A. A. Doinikov

Abstract

A one-dimensional numerical model has been developed for the interaction of an ultrasound field with a free and an encapsulated gas bubble immersed in a liquid. The model includes several approaches to simulations of this type. First, the calculation of the radius of the bubble can be performed by Rayleigh–Plesset-type equations, while the distribution of the gas-dynamic parameters within the bubble is calculated by solving the equations of gas dynamics which are represented in terms of Lagrangian coordinates. Second, a through calculation can be carried out by solving the equations of fluid dynamics for both the interior of the bubble and the surrounding liquid. These numerical approaches can be applied to both free and encapsulated (contrast agent) bubbles. In the case of an encapsulated bubble, the equations describing the radial oscillation of a bubble enclosed in a fluid or solid shell are used. Simulations for a wide range of driving frequencies and bubble radii have been conducted. The obtained results demonstrate wide capabilities of the developed model. Keywords: contrast agents, encapsulation, ultrasound, fluid dynamics, radial oscillation, rheological behaviour, numerical simulation. 1 Introduction The wide application of ultrasound contrast agents in medicine and the variety of materials used for the encapsulation of contrast agent microbubbles have given rise to numerous theoretical, numerical and experimental investigations in this field [1]. The non-Newtonian behaviour of blood and intricate rheological properties of encapsulating shells hamper the theoretical description of the dynamics of contrast agents in an ultrasound field. Depending on their material,

Keywords

contrast agents, encapsulation, ultrasound, fluid dynamics, radial oscillation, rheological behaviour, numerical simulation.