background: aneurysm is a blood-filled bulge in the wall of vessels that occurred in abdominal aortic and cerebral vessels. the dilation of artery leads to aneurysm. methods: three dimensional modelling was utilized for a patient with cerebral aneurysm and a normal subject, and additional fluid-structural interaction simulation was performed. we consider pulsatile blood velocity as inlet, and b...

We investigate the stability of a Helmholtz velocity profile in a stably stratified fluid when a lower boundary is present. In addition to the traditional Kelvin-Helmholtz interfacial instability we find an infinitude of unstable internal gravity waves, the most unstable of which bear a close resemblance to disturbances observed in connection with clear air turbulence. It is shown that the grav...

Shallow shear wave reflection surveys using high frequency vibroseis techniques provides information about the Tertiary bedrock surface and Pleistocene sediments on the Fraser River delta, in B.C., Canada. Besides the clear advantage of shear wave profiling in this shallow gas environment, the added resolution potential and ability to measure the shear wave velocity field enhances the fusion of...

Ultrafast imaging using plane or diverging waves has recently enabled new ultrasound imaging modes with improved sensitivity and very high frame rates. Some of these new imaging modalities include shear wave elastography, ultrafast Doppler, ultrafast contrast-enhanced imaging and functional ultrasound imaging. Even though ultrafast imaging already encounters clinical success, increasing even mo...

Some of the first acoustic well logs were done in the 1950s by Vogel [l]. The tool (commonly called a sonde) used for these logs consisted of one transmitter and one or two receivers. At that time only a rudimentary knowledge of the acoustics of the borehole was known; however, it was known that the compressional wave in the formation would be the first to effect the received signal. Using this...

In this work, the problem of Rayleigh wave propagation is considered in the context of the theory of thermoelastic diffusion. The formulation is applied to a homogeneous isotropic thermoelastic half space with mass diffusion at the stress free, isothermal, isoconcentrated boundary. Using the potential functions and harmonic wave solution, three coupled dilatational waves and a shear wave is obt...

A novel torsional wave sensor designed to characterize mechanical properties of soft tissues is presented in this work. Elastography is a widely used technique since the 1990s to map tissue stiffness. Moreover, quantitative elastography uses the velocity of shear waves to achieve the shear stiffness. This technique exhibits significant limitations caused by the difficulty of the separation betw...

We perform numerical experiments with a novel cellularautomaton fluid model. The model has simple pair-interaction rules and works in arbitrarily many dimensions; here we consider the twodimensional case. By observing the smoothing-out of the velocity profile of a shear flow and the relaxation of a shear wave, we measure the kinematic shear viscosity and obtain a value of :::::: 0.5. To demonst...