Discussion Forum

I am trying to simulate ultrasound propagation from an ultrasound transducer in a water tank with a slab of higher acoustic impedance material placed in the middle of the tank. The goal is to develop an understanding of what the ultrasound pressure field should look like when I introduce acoustic impedance mismatch into the pressure field. Based on the acoustic impedance mismatch of water vs the theoretical high acoustic impedance material I have added, I have calculated that there should be close to 100% reflection of the ultrasound waves at the water-high impedance material interface, however in my results I am consistently seeing high transmission of the ultrasound waves into the high impedance material block as well as some strange reverberation artifacts inside the high impedance material.

I am using the frequency domain pressure acoustics module & defining my transducer as a flat line with normal displacement (piston transducer). I defined the water & high impedance material mediums in the pressure acoustics module with a user defined attenuation. From my understanding, the pressure acoustics module should have the ability to compare acoustic impedance of the high impedance material and water material domains and define reflection / transmission coefficients based on the acoustic impedance mismatch, but this doesnt seem to be working.

Also, if I swap the high impedance material and water mediums with each other (slab of water in a high impedance material tank), I have almost full reflection of the ultrasound waves at the high impedance material-to-water boundry. It looks like for some reason I have the expected reflection only when travelling from domains of high acoustic impedance to low acousic impedance, but not low acoustic impedance to high acoustic impedance.

Does anyone have any ideas of what could be causing this? I have included an image of the pressure field without any high impedance material slab, as well as the pressure field with the slab inserted into the tank.