Coupled Pulsation And Translation Of A Gas Bubble And Rigid Particle

A nonlinear analytic model describing the interaction of a spherical gas bubble and spherical rigid particle is presented. Both the bubble and particle are free to translate. The model is accurate to fifth order in terms of a nondimensional expansion parameter R/d, where R is a characteristic radius and d is the distance separating the bubble and particle. Numerical simulation results are presented to demonstrate the effects of key particle parameters and an external acoustic source.Applied Research Laboratorie

Nonlinear Torsional Wave Beams

An evolution equation with cubic nonlinearity is presented for a torsional wave beam in an isotropic elastic solid. Analytical solutions are presented for the fundamental and third harmonic in the far field of a uniform circular source. Numerical results are presented for harmonic beam patterns at an intermediate distance between the near and far fields, and for a torsional waveform with shocks.Applied Research Laboratorie

Model For The Dynamics Of A Bubble Undergoing Small Shape Oscillations Between Elastic Layers

A model is presented for a pulsating and translating gas bubble in a channel formed by two soft elastic parallel layers. The bubble is free to undergo small shape deformations. Coupled nonlinear second-order differential equations are obtained for the shape and position of the bubble, and numerical integration of an expression for the liquid velocity at the layer interfaces yields an estimate of their displacement. Simulations reveal behavior consistent with laboratory observations.Applied Research Laboratorie

Acoustic Radiation Force On A Sphere In Tissue

A theory is presented for the acoustic radiation force on a sphere embedded in a soft elastic medium that possesses a shear modulus several orders of magnitude smaller than its bulk modulus. Scattering of both compressional and shear waves is taken into account. There is no restriction on the size of the sphere or, apart from symmetry about an axis passing through the center of the sphere, the form of the incident compressional wave. If the medium is a liquid and the sphere is small in comparison with a wavelength the result reduces to the classical theory developed by Gor'kov [1] and others. The effect of shear elasticity on the radiation force is discussed in the context of parameters relevant to a gas bubble in tissue.Applied Research Laboratorie