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TRCM

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

Overview

Benchmarked Unvalidated
Theory Implementation

These pages come from the high-frequency elongated-body literature and later fish and zooplankton applications (Stanton et al. 1993, 1998; Stanton, Chu, and Wiebe 1998).

The two-ray cylinder model (TRCM) is a high-frequency asymptotic family for elongated fluid-like bodies. It retains only two dominant coherent paths: a prompt near-side reflection and a through-body path that returns after an internal reflection.

Core idea

Replace the full internal reverberation problem by the first two physically important ray paths and compute the target strength from their interference, combined with a finite-length directivity factor.

Best for

  • High-frequency elongated fluid-like targets
  • Cylinder-like bodies whose scattering is dominated by specular path interference
  • Fast asymptotic estimates when a full modal or perturbative solve is unnecessary

Supports

  • Straight and bent cylindrical-style branches
  • Contrast notation relative to seawater as medium 1
  • Monostatic high-frequency backscatter estimates

Main assumptions

  • High-frequency regime
  • Only two dominant coherent internal/external paths are retained
  • No low-order resonances or full internal multiple scattering series

Validation status

  • Benchmarked within the package validation workflow against the straight-cylinder and FCMS-derived bent-cylinder reference constructions.

Family pages

  • Implementation: usage and comparison workflows
  • Theory: two-ray geometry, interference factor, and finite-length 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.
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.