Radiation force in nonlinear, focused beams.
The effect of cumulative nonlinear distortions in a focused ultrasonic wave on the dissipative radiation force (RF) is analyzed using a simplified analytical model separating the stages of geometrical focusing and the subsequent diffraction in the focal area. It is shown that in the absence of shocks, nonlinear steepening can significantly amplify the RF as compared with a harmonic wave. Two different types of dissipation, one corresponding to a classical viscous fluid and another typical of many biological tissues, are considered.
Ostrovsky
L A
LA
Zel Technologies/NOAA Earth System Research Laboratory/University of Colorado, 325 Broadway, Boulder, Colorado 80027, USA. lev.a.ostrovsky@noaa.gov
D001826:Body Fluids / Q000737:chemistry; D004548:Elasticity; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D012542:Scattering, Radiation; D014465:Ultrasonics; D014783:Viscosity