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BBFM

Source: vignettes/bbfm/index.Rmd
index.Rmd

Overview

Unvalidated Experimental
Theory Implementation

The body-backbone fish model (BBFM) is a composite model for swimbladder-less fish in which the flesh body and an elastic backbone are retained as separate acoustic components.

Core idea

Calculate the flesh-body contribution with DWBA, calculate the backbone with ECMS, translate both amplitudes into one body-fixed phase reference, and add them coherently. This separates mechanisms emphasized in swimbladder-less fish models (Gorska et al. 2005; Stanton et al. 1998).

Best for

  • Swimbladder-less fish with explicit body and backbone geometry
  • Studying interference between weak-fluid flesh and an elastic internal component
  • A transparent first-order composite approximation before a coupled solver is available

Supports

  • BBF objects constructed from separate body and backbone Shape objects
  • Fluid-like body properties and elastic backbone density and wave speeds
  • Stored body, backbone, phase-shifted, and combined outputs

Main assumptions

  • The flesh remains within the DWBA weak-scattering regime
  • The backbone is represented by the canonical ECMS cylinder solution
  • Centroid translation is sufficient to place the component phases
  • No shadowing, repeated rescattering, or coupled embedded-cylinder boundary solve

Validation status

  • BBFM is currently marked experimental because it has documented internal reconstruction checks but no external benchmark ladder or independent public implementation comparison.

Family pages

  • Implementation: constructing BBF objects, component output, and reconstruction checks
  • Theory: component amplitudes, phase translation, and interference
  • Combining components: requirements for coherent and incoherent sums

References

Gorska, Natalia, Egil Ona, and Rolf Korneliussen. 2005. “Acoustic Backscattering by Atlantic Mackerel as Being Representative of Fish That Lack a Swimbladder. Backscattering by Individual Fish.” ICES Journal of Marine Science 62 (5): 984–95. https://doi.org/10.1016/j.icesjms.2005.03.010.
Stanton, Timothy K., Dezhang Chu, Peter H. Wiebe, Linda V. Martin, and Robert L. Eastwood. 1998. “Sound Scattering by Several Zooplankton Groups. I. Experimental Determination of Dominant Scattering Mechanisms.” The Journal of the Acoustical Society of America 103 (1): 225–35. https://doi.org/10.1121/1.421469.