2023_programme: Using effective medium modeling and additive manufacturing to evaluate acoustic behavior of seagrasses

• Session: 10. Observing the Oceans Acoustically
  Organiser(s): Bruce Howe and Kai Gemba
• Lecture: Using effective medium modeling and additive manufacturing to evaluate acoustic behavior of seagrasses
  Paper ID: 2040
  Author(s): Cushing Colby W., Jerome Thomas S., Ballard Megan S., Lee Kevin M., Naify Christina J., Allison Jared A., Capistrant-Fossa Kyle A., McNeese Andrew R., Wilson Preston S., Dunton Kenneth H.
  Presenter: Cushing Colby W.
  Abstract: Motivated by declines in global seagrass populations and interest in novel techniques to inform conservation efforts, acoustic remote sensing has been established as an effective means to monitor changes in seagrass meadow environments by exploiting the sensitivity of acoustic propagation to gas bubbles produced by photosynthesis or encapsulated within the seagrass leaves. Subsequent studies conducted to quantify the effect of seagrass on acoustic propagation have employed a number of possible simple effective medium models and numerical techniques, and have been successful in characterizing a number of acoustic and elastic properties for various seagrass tissues. These studies concluded that the simple effective medium models considered do not sufficiently address the internal structure of seagrass tissue, and thus the need remains for a computationally-efficient, comprehensive acoustic model to describe the effect of seagrasses on acoustic propagation that includes effects associated with the elastic properties of seagrass tissue and encapsulated gas channels. The present talk provides an overview of continuing developments in the modeling of acoustic propagation in a meadow of Thalassia testudinum using an acoustic effective medium approach. The proposed analysis represents the seagrass leaves using a micromechanical spring-mass-damper model based on the internal microstructure of an individual leaf. This model is compared to a semi-analytical model following the multiple scattering framework of Linton and Martin [doi:10.1137/050636401] and represents the seagrass meadow as a random configuration of elastic cylindrical shells. To test the applicability of the models, artificial seagrass was designed and fabricated using additive manufacturing techniques to isolate the structural effects on sound propagation while eliminating the unpredictability of biological processes in natural seagrass. Results from the proposed and previous acoustic models will be compared to preliminary evaluations of the artificial seagrass as well as ongoing experiments of seagrass meadow monitoring along the Texas Gulf Coast. [Supported by NSF, ARLUT.]
• Corresponding author: Dr Colby W. Cushing
  Affiliation: Applied Research Laboratories at the University of Texas at Austin
  Country: United States
  e-mail: