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VESM

Source: vignettes/vesm/index.Rmd
index.Rmd

Overview

Validated Experimental
Theory Implementation

These pages are motivated by layered gas-bearing fish scattering models and viscous resonance broadening (Khodabandeloo et al. 2021; Feuillade and Nero 1998).

The viscous-elastic spherical model (VESM) is a layered spherical resonance family for a gas core surrounded by an elastic shell and an outer viscous biological layer.

Core idea

Solve the spherical layered problem mode by mode, with acoustic waves in the exterior and gas core, viscous compressional/shear branches in the soft outer layer, and elastic longitudinal/transverse waves in the shell.

Best for

  • Gas-bearing mesopelagic-fish style layered spheres
  • Problems where gas resonance, shell elasticity, and viscous damping all matter simultaneously
  • Wideband spherical resonance studies beyond a simple bubble or shell-only idealization

Supports

  • ESS spherical objects with an explicit shell and inner gas core plus viscous-layer model arguments
  • Four-region spherical bookkeeping with seawater as medium 1
  • Monostatic layered resonance calculations

Main assumptions

  • Spherical symmetry
  • Homogeneous material properties within each layer
  • Linear acoustics and linear elasticity
  • Layered spherical interfaces with no nonspherical posture or geometry effects

Validation status

  • Validated against the reference Python VESM implementation on the documented layered-sphere case.
  • VESM is currently marked experimental because the documented public workflow is still limited to the current layered-sphere scope.

Family pages

  • Implementation: layered-object workflow and benchmark comparisons
  • Theory: full layered spherical field structure, interface conditions, and mode-wise systems

References

Feuillade, C., and R. W. Nero. 1998. “A Viscous-Elastic Swimbladder Model for Describing Enhanced-Frequency Resonance Scattering from Fish.” The Journal of the Acoustical Society of America 103 (6): 3245–55. https://doi.org/10.1121/1.423076.
Khodabandeloo, Babak, Mette Dalgaard Agersted, Thor Klevjer, Gavin J. Macaulay, and Webjørn Melle. 2021. “Estimating Target Strength and Physical Characteristics of Gas-Bearing Mesopelagic Fish from Wideband in Situ Echoes Using a Viscous-Elastic Scattering Model.” The Journal of the Acoustical Society of America 149 (1): 673–91. https://doi.org/10.1121/10.0003341.