title: Time-domain modeling of nonlinear distortion of pulsed finite amplitude sound beams.
abstract: This work aims to validate a time domain numerical model for the nonlinear propagation of a short pulse of finite amplitude sound beam propagation in a tissue-mimicking liquid. The complete evolution equation is simply derived by a superposition of elementary operators corresponding to the 'one effect equation'. Diffraction LD, absorption and dispersion LAD, and nonlinear distortion LNL effects are treated independently using a first order operator-splitting algorithm. Using the method of fractional steps, the normal particle velocity and the acoustical pressure are calculated plane by plane, at each point of a two-dimensional spatial grid, from the surface of the plane circular transducer to a specified distance. The LA operator is a time convolution between the particle velocity and the causal attenuation filter built after the Kramers-Kroning relations. The LNL operator is a time-based transformation obtained by following an implicit Poisson analytic solution. The LD operator is the usual Rayleigh integral. We present a comparison between theoretical and experimental temporal pressure waveform and axial pressure curves for fundamental (2.25 MHz), second, third and fourth harmonics, obtained after spectral analysis.
authors.affiliation: GIP ULTRASONS/LUSSI EA 2102, Tours, France. remenier@med.univ-tours.fr
authors.forename: J P
authors.initials: JP
authors.lastname: Remenieras
authors.forename: O
authors.initials: O
authors.lastname: Bou Matar
authors.forename: V
authors.initials: V
authors.lastname: Labat
authors.forename: F
authors.initials: F
authors.lastname: Patat
mesh_terms: D000042:Absorption; D000162:Acoustics; D000465:Algorithms; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D019047:Phantoms, Imaging; D014463:Ultrasonography