University of Cambridge > Talks.cam > Engineering Department Geotechnical Research Seminars > Washboard Road: The dynamics of granular ripples

Washboard Road: The dynamics of granular ripples

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  • UserProf Jim McElwaine, BA,MA,MMath,CASM,PhD, Professor of Geohazards, Department of Earth Sciences, Durham University and the Planetary Science Institute Tucson
  • ClockThursday 16 January 2014, 16:00-17:30
  • HouseEngineering Department - Lecture Room 4.

If you have a question about this talk, please contact Anama Lowday.

Granular surfaces tend to develop lateral ripples under the action of surface forces exerted by rolling wheels, an effect known as washboard or corrugated road. We report the results of both laboratory experiments and soft-particle direct numerical simulations. Above a critical speed, the ripple pattern appears as small patches of traveling waves which eventually spread to the entire circumference. The ripples drift slowly in the driving direction. Interesting secondary dynamics of the saturated ripples were observed, as well as various ripple creation and destruction events. All of these effects are captured qualitatively by 2D soft particle simulations in which a disk rolls over a bed of poly-disperse particles in a periodic box. These simulations show that compaction and segregation are inessential to the ripple phenomenon. We show how a simplified scaling model gives insight into the mechanism of the instability and discuss the applicability of a weakly non-linear theory.

This talk is part of the Engineering Department Geotechnical Research Seminars series.

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