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Dynamics and adjustment of wave ripples

Join MIT researchers in a study of wave ripple evolution under controlled conditions. Discover how ripples form and evolve as sand in suspension settles, showcasing the process through time-lapse experiments in shallow water environments. Exploration of flow separation, deposition, and erosion phenomena unfold through spotlight-illuminated experiments replicated in a field-scale wave tank. Witness the impact of wave variations on ripple wavelength in an immersive study of sediment transport dynamics.

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Dynamics and adjustment of wave ripples

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  1. Dynamics and adjustmentof wave ripples • Colleagues at • Massachusetts Institute of Technology • Taylor Perron, Justin Kao, Kim Huppert, Abby Koss, Jocelyn Fuentes, and John Southard

  2. Waves generate oscillating flow near bed Airy, shallow water: Clifton & Dingler [1984] Sand in suspension settles in troughs Ripples arise from an instability in sediment transport over bed perturbations. Avalanching + settling limit growth • Flow separation • τ drops, • deposition Flow accelerates over bump increasing τ, erosion For flow to the right: Avalanching 3 cm

  3. Field-scale wave tank experiments to study ripple evolution under controlled conditions Spotlight illumination Time-lapse camera triggered every N wave periods (experiments last >104 periods) Variable-speed electric motor drives paddle 0.18 mm sand, water depth 30-40 cm “Beach” of polymer mats damps reflection Open duct 60 cm wide x 50 cm deep

  4. Ripples spreading from an initial bump Light direction 30 cm 1 second in movie = 10 minutes real time

  5. Experiments • Initial bed grown from leveled, raked sand to equilibrium ripple wavelength • Step change in wave orbital diameter causes ripple wavelength to lengthen or shorten by up to 5 cm Light direction 40 cm 1 second in movie = 10 minutes real time

  6. Experiments • Initial bed grown from leveled, raked sand to equilibrium ripple wavelength • Step change in wave orbital diameter causes ripple wavelength to lengthen or shorten by up to 5 cm Light direction 40 cm 1 second in movie = 10 minutes real time

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