Comparison of fundamental, second harmonic, and superharmonic imaging: A simulation study

In medical ultrasound, fundamental imaging (FI) uses the reflected echoes from the same spectral band as that of the emitted pulse. The transmission frequency determines the trade-off between penetration depth and spatial resolution. Tissue harmonic imaging (THI) employs the second harmonic of the emitted frequency band to construct images....

Direct analysis of dispersive wave fields from near-field pressure measurements

Flexural waves play a significant role for the radiation of sound from plates. The analysis of flexural wave fields enables the detection of sources and transmission paths in plate-like structures. The measurement of these wave fields can be carried out indirectly by means of near-field acoustic holography, which determines the vibrational wave...

Dispersive surface waves along partially saturated porous media

Numerical results for the velocity and attenuation of surface wave modes in fully permeable liquid/partially saturated porous solid plane interfaces are reported in a broadband of frequencies (100?Hz–1?MHz). A modified Biot theory of poromechanics is implemented which takes into account the interaction between the gas bubbles and both the liquid...

Retrieving the Green’s function in an open system by cross correlation: A comparison of approaches (L)

We compare two approaches for deriving the fact that the Green’s function in an arbitrary inhomogeneous open system can be obtained by cross correlating recordings of the wave field at two positions. One approach is based on physical arguments, exploiting the principle of time-reversal invariance of the acoustic wave equation. The other approach...

The role of sound propagation in concentrated colloidal suspensions

In a suspension, the hydrodynamic interactions between particles can propagate by two mechanisms: relatively slowly, by the diffusion of transverse momentum, or relatively rapidly, by the propagation of sound waves. Here we describe computer simulation results for the collective and single particle dynamics of colloidal particles with the aim of...