Cartesian normal-mode models for a mid-size laboratory water tank

A laboratory water tank at Brigham Young University is being characterized, and a suitable model is needed to describe the sound propagation, which includes realistic boundary conditions. Two Cartesian normal-mode models are compared: one begins with pressure release boundary conditions then adds wall losses and the other begins with rigid boundary conditions for the walls and incorporates finite impedance through spatially averaged absorption. The models are updated to remove assumptions for smaller glass tanks and to include estimates of the characteristic acoustic impedance of the wall material. Each model is sensitive to the number of modes used. The modeled transmission loss values at 10 Hz to 100 kHz are computed for the rectangular acrylic tank (3.6 m x 1.2 m wide with water depths of 0.47 m and 0.24 m x 0.48 m). The modeled values are compared to measured data via relative transmission loss estimates as a function of distance. The tank sound propagation model will allow us to model our tank, simulate the sound field for optimization problems, and create accurate training data for machine learning applications.