Charles E. Bradley

Acoustic streaming field structure. Part II. Examples that include boundary-driven flow.

In this paper three simple acoustic streaming problems are presented and solved. The purpose of the paper is to demonstrate the use of a previously published streaming model by Bradley [J. Acoust. Soc. Am. 100(3), 1399-1408 (1996)] and illustrate, with concrete examples, some of the features of streaming flows that were predicted by the general model. In particular, the problems are intended to demonstrate cases in which the streaming field boundary condition at the face of the radiator has a nontrivial lateral dc velocity component. Such a boundary condition drives a steady solenoidal flow just like a laterally translating boundary drives Couette flow.

Dynamic color Doppler extended field of view imaging

A new method for generating dynamic color Doppler extended field of view (EFOV) images is presented. The method derives an ECG waveform from the spatial average of Doppler velocity data from a series of co-planar ultrasonic images acquired by translating the probe in the azimuth direction. Translation and rotation parameters between successive images are estimated using speckle correlation of the B-mode data. The images corresponding to the same phase of the synthetic ECG are then combined using, these, motion parameters to form a color Doppler EFOV image. A series of these color Doppler EFOV images are generated corresponding, to, different cardiac phases. These images are then played back in a continuous loop over the B-mode EFOV image.