Hello guys! I have to model the acouctic field within partially filled cavities. So consider a rectangular or cylindrical cavity that is partially filled with water. I would like to model the water layer as a sound absorbing wall by prescribing it as a surface impedance boundary condition. My problem is modelling the surface impedance of water. Are there any standard surface impedance models for fluids like water? Or how should I model the surface impedance for water? I'm also open for any other suggestions in approaching the water layer as a sound absorbing wall. Thanks for your answers!