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4.6 Exercise 7: Long Waves in a Layered Fluid 85Fig. 4.17 Configuratio for Exercise 74.6.3 Sample Code and Animation ScriptThe folder “Exercise 7” on the CD-ROM contains the computer codes for this exercise.The “info.txt” gives additional information.4.6.4 ResultsA relatively short forcing period of 10 s creates barotropic surface gravity waves(Fig. 4.18). Density interfaces oscillate in unison with the sea surface. The phasespeed of the wave is c ≈ √ gH, where H is total depth of the water column. Wavesapproaching the riff pile up while their wavelength decreases. The wave thereforebecomes steeper aiming to break. Indeed, wave breaking cannot be simulated witha layer model. Notice that waves continue to propagate eastward on the lee side ofthe riff.When watching the real sea patiently, riffs or sandbars can be identifie as theregions with locally increased wave heights and wave breaking. This process isknown as wave shoaling.Fig. 4.18 Exercise 7. Snapshot of surface and interface displacements for a forcing period of 10 s.Only the top 40 m of the water column are shown