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| Titel |
Particle size-segregation and roll waves in geophysical mass flows |
| VerfasserIn |
Sylvain Viroulet, Andrew Edwards, Peter Kokelaar, Nico Gray |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096133
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| Publikation (Nr.) |
 EGU/EGU2014-11620.pdf |
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| Zusammenfassung |
| Particle size-segregation in geophysical mass flows can have a profound feedback on their
local mobility, leading to the formation of resistive bouldery flow fronts, which
spontaneously degenerate into leveed channels [1,2] that constrain the flow and enhance
run-out. By including particle segregation [3], a composition dependent frictional coupling
can be incorporated into depth-averaged geophysical mass flow models to capture both levee
formation and flow fingering [4]. However, the channel wavelengths are crucially dependent
on the underlying rheology of the flow, which is a second order effect that is still not fully
understood. In this paper we analyze a simpler, but closely related, mono-disperse flow
in which the granular rheology plays a crucial part in the formation, growth and
coarsening of roll waves. Two regimes have been found experimentally:- (i) a classical
continuous roll wave regime, and (ii) a novel discrete roll wave regime where the
troughs between the wave peaks become completely stationary. This latter behaviour
has been observed in debris flows in Fully, Switzerland, and the Jiangjia Gully,
China.
Grain-size segregation and levee formation in geophysical mass flows, Johnson,
C.G., Kokelaar, B.P., Iverson, R.M., Logan, M., LaHusen, R.G. & Gray, J.M.N.T.
(2012) J. Geophys. Res. 117, F01032.
Fine-grained linings of leveed channels facilitate runout of granular flows,
Kokelaar, B.P., Graham, R.L., Gray, J.M.N.T. & Vallance, J.W. (2014) Earth
Planet. Sci. Lett. 385, 172-180.
Large particle segregation, transport and accumulation in granular free-surface
flows. Gray, J.M.N.T. & Kokelaar, B.P. (2010) J. Fluid Mech. 652, 105-137.
Segregation-induced fingering instabilities in granular free surface flows,
Woodhouse, M.J., Thornton, A.R., Johnson, C.G., Kokelaar, B.P. & Gray,
J.M.N.T. (2012) J. Fluid Mech. 709, 543-580. |
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