12: Submerged Bar Benchmark (Beji & Battjes) #22
Description
Description
Simulate the classic Beji & Battjes (1994) submerged bar experiment and compare with laboratory data. This is the primary experimental validation case.
Background
Waves propagate over a trapezoidal bar, undergo nonlinear shoaling, and release bound harmonics as free waves. This tests:
- Variable bathymetry handling
- Nonlinear wave-wave interactions
- Accurate dispersion (free harmonics travel at different speeds)
Tasks
- Define bar geometry (Case A from original experiment)
- Offshore depth: h₀ = 0.4 m
- Bar top depth: h_bar ≈ 0.1 m
- Up-slope: 1:20
- Down-slope: 1:10
- Set up numerical wave tank
- Generation zone at inlet
- Absorption zone at outlet
- Sufficient length for full bar + propagation
- Configure input wave
- H = 0.02 m
- T = 2.02 s
- Stream function solution at depth h₀
- Implement gauge output at experimental locations
- x = 4, 10.5, 13.5, 14.5, 15.7, 17.3, 19.0, 21.0 m
- Run simulation for 40+ seconds
- Compare with experimental data
Acceptance Criteria
- Simulation runs stably for full duration
- Harmonic generation visible in time series over bar
- Free harmonic dispersion visible after bar
- Time series qualitatively match experimental data
- Peak amplitudes within 20% of experimental values
- Phase agreement within 10%
Deliverables
- Time series plots at each gauge location
- Overlay with experimental data
- Spatial snapshot of wave field over bar
- Animation of full simulation
References
- Beji, S. and Battjes, J.A. (1994) "Numerical simulation of nonlinear wave propagation over a bar"
- Luth et al. (1994) experimental data