Ripples and Waves *

Water Waves over Ripples

The interaction of small amplitude water waves with a patch of bottom ripples is studied using the Boundary Integral Equation Method (BIEM). Normal and oblique wave incidence is examined for reflection coefficients and the laboratory data of Davies and Heathershaw are compared to the numerical results, with the conclusion that the analytical model of Davies and Heathershaw overestimates the ref...

Slow waves, sharp waves, ripples, and REM in sleeping dragons.

Sleep has been described in animals ranging from worms to humans. Yet the electrophysiological characteristics of brain sleep, such as slow-wave (SW) and rapid eye movement (REM) activities, are thought to be restricted to mammals and birds. Recording from the brain of a lizard, the Australian dragon Pogona vitticeps, we identified SW and REM sleep patterns, thus pushing back the probable evolu...

Dynamical models for sand ripples beneath surface waves.

We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass transport function, our models predict the existence of a stable band of wave numbers limited by second...

Temporal Variation of Suspended Sediment Concentration for Waves over Ripples

Variations of suspended sediment concentration over ripples in regular waves were described using an existing numerical model system. Nielsen’s (1992) empirical formula for sediment entrainment rate from the bed surface was used with an additional scale factor in the model system. The model system was applied to two typical laboratory experimental conditions selected for description of the vari...

A particle model of rolling grain ripples under waves