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TRCM

Source: vignettes/trcm/index.Rmd
index.Rmd

Overview

Benchmarked Unvalidated
Theory Implementation

The two-ray cylinder model (TRCM) is a high-frequency approximation for fluid-like cylindrical targets whose response is dominated by two coherent cross-sectional ray paths.

Core idea

Retain a prompt near-side reflection and a transmitted path that returns after one internal reflection. Their interference is multiplied by the finite-length directivity term (Stanton et al. 1993, 1998).

Best for

  • Acoustically large, locally cylindrical fluid-like targets
  • Interpreting high-frequency interference between reflected and transmitted paths
  • Fast comparison with finite-cylinder modal calculations

Supports

  • Cylindrical FLS scatterers with density and sound-speed contrasts
  • Straight or uniformly curved centerline geometry represented by the current TRCM interface
  • Monostatic complex amplitude, cross-section, and target strength

Main assumptions

  • A high-frequency ray regime and locally circular cross-section
  • Only the two leading coherent ray paths are retained
  • No low-order modal resonances or full internal reverberation series
  • Finite-length and curvature effects enter through approximate coherence factors

Validation status

  • Benchmarked within the package validation workflow against the canonical spectra stored in benchmark_ts. Further compared to the straight-cylinder and FCMS-derived bent-cylinder reference constructions.

Family pages

  • Implementation: geometry, output, and reference comparisons
  • Theory: ray paths, interference, and axial directivity

References

Stanton, Timothy K., Dezhang Chu, and Peter H. Wiebe. 1998. “Sound Scattering by Several Zooplankton Groups. II. Scattering Models.” The Journal of the Acoustical Society of America 103 (1): 236–53. https://doi.org/10.1121/1.421110.
Stanton, Timothy K., Dezhang Chu, Peter H. Wiebe, and Clarence S. Clay. 1993. “Average Echoes from Randomly Oriented Random-Length Finite Cylinders: Zooplankton Models.” The Journal of the Acoustical Society of America 94 (6): 3463–72. https://doi.org/10.1121/1.407200.