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Dynamical evolution of sand ripples under water
1Laboratoire de Météorologie Dynamique, ENS, 24 Rue Lhomond, 75231 Paris, France.
Summary
Sand ripples evolve irreversibly in oscillatory flow, reaching stable patterns governed by fluid dynamics and granular properties. Hysteresis and fluidization influence steep ripple development and final configurations.
Area of Science:
- Fluid dynamics
- Geomorphology
- Granular physics
Background:
- Sand ripples are common geomorphological features formed by fluid flow.
- Understanding ripple evolution is crucial for sediment transport and coastal processes.
Purpose of the Study:
- To experimentally investigate the evolution of sand ripples under oscillatory flow.
- To identify key parameters governing ripple formation and stability.
Main Methods:
- Utilized an annular sand-water cell for controlled experiments.
- Varied parameters to observe ripple pattern development.
Main Results:
- Observed an irreversible condensation mechanism in ripple evolution.
- Identified fluid displacement and static granular angle as primary governing factors.
- Noted hysteresis effects and superficial fluidization impacting steep ripples.
Conclusions:
- Sand ripple evolution follows predictable patterns under oscillatory flow.
- Fluid and granular properties dictate stable sand pattern characteristics.
- Critical acceleration can lead to sand layer fluidization, altering final patterns.