Overview
This family is best read alongside the swimbladder-less fish and composite-scatterer literature that motivates explicit flesh-body and backbone terms (Gorska, Ona, and Korneliussen 2005; Stanton et al. 1998; Clay and Horne 1994).
The body-backbone fish model (BBFM) is the package’s
composite swimbladder-less family for targets whose flesh body and
backbone should remain explicit acoustic components.
Core idea
Compute a weak-fluid flesh-body term with DWBA, compute
an elastic backbone term with ECMS, place the backbone
inside the same body-fixed frame with a two-way phase factor, and then
sum the two complex amplitudes coherently.
Best for
- Swimbladder-less fish where the backbone should remain acoustically explicit
- Composite body-plus-backbone studies that are too structured for a body-only approximation
- Intermediate modeling between weak-fluid body models and future fully coupled composite solvers
Supports
-
BBFscatterers built from explicitbody_shapeandbackbone_shapeinputs - Flesh-body material properties as contrasts or absolute density/sound speed
- Backbone density plus longitudinal and transverse elastic wave speeds
Main assumptions
- Flesh body treated in the weak-fluid
DWBAregime - Backbone treated as an elastic cylinder through
ECMS - Components combined coherently after centroid-based phase placement
- No repeated rescattering or fully coupled embedded elastic-cylinder 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: object setup, stored outputs, and internal reconstruction checks
- Theory: composite amplitude, phase placement, and interference structure
BBFM is already useful as a transparent composite
family, but it should still be treated as experimental. The main open
work is external validation and, in the longer term, a more tightly
coupled treatment of the backbone as an embedded elastic structure
rather than a positioned component surrogate.
Why it exists
BBFM fills the gap between:
- body-only weak-scattering models that ignore the backbone,
- and future fully coupled body-plus-backbone solvers that are not yet in the package.
That is why the family belongs in acousticTS even before a more complete composite solver exists: it gives a physically interpretable way to keep the two dominant anatomical components explicit in one coherent target-strength calculation.