Learning Forum

[MostafaOdabaee]

Hi there,

I’m trying to run a FSI steady-state harmonic acoustic simulation to estimate the attenuation of human skull exposed to ultrasound waves. I have basically the activated surface of the transducer (surface velocity), two acoustic regions (water, as the coupling medium between the surface of transducer and skull and also inside skull), one physics region (human skull), and FSI. The properties of human skull are shown in one of the attached pictures. However, this is not showing a noticeable amount of pressure drop (attenuation) once the ultrasound waves propagate through the skull. In another word, the transmitted pressure is not attenuated. I was wondering if someone could kindly help me to find the right solution for this? Thanks. Mostafa

 

[Hui Liu]

Hi Mostafa,

what is your mesh look like, and what's your frequency range for your solution? Is your element size small enough? 

[MostafaOdabaee]

Hi HuiLiu,

Thank you for your post.

The mesh size equals tenth of dominant wavelength (=0.625mm) for a frequency range of below 350kHz.. I think it is fine enough.

[sk_cheah]

Hi Mostafa,

From the images you posted, it looks like your analysis is 2D. That may be the problem. In 19.2 documentation on Harmonic Acoustic Analysis, it states: 

This analysis supports 3D geometries only

Kind regards,
Jason

[MostafaOdabaee]

 

Hi Jason,

 

Thanks for your comment. Yes, that view is misleading. But actually it is in 3D. The entire domain has a cylindrical symmetry shape and I just considered a 5 degree of the whole 360 degree, see the top view, below.