Discussion Forum

Hello,

I am trying to simulate a large gold particle (10mm diameter) suspended in a water tank and exposed to ultrasound waves. I want to visualize the pressure and intensity field around the gold particle as ultrasound waves are scattered at the water-gold interface. To simulate my ultrasound waves, I am using the pressure acoustics module with a flat line assigned a displacement (piston transducer). All water domains are simulated with the pressure acoustics module, while the gold particle is simulated using the solid mechanics module.

I also have the option to assign the acoustic-structure boundry to the water-gold interface using COMSOLs multiphysics option but am seeing some weird things happening when using it. If I don't use the acoustic-structure boundry I see very little transmission through the gold particle & disruption of the ultrasound pressure field around the particle (figure attached). If I use the acoustic-structure boundry assigned at the water-gold interface, I see a large spike in pressure at the side of the gold particle opposite the ultrasound transducer. Looking at the axial pressure profile through the gold particle, I see a large increase in pressure, when in reality it should be decreasing significantly due to reflection and attenuation. Based on my knowledge of ultrasound reflection at the water-gold interface and attenuation when passing through the gold nanoparticle, it makes no sense that pressure would increase after passing through the gold particle. To me, it looks like by adding in the acoustic-structure boundry with COMSOLs multiphysics something is going wrong with the pressure calculations. Does anyone know why this could be happening?