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| Titel |
Modelling debris flows down general channels |
| VerfasserIn |
S. P. Pudasaini, Y. Wang, K. Hutter |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 5, no. 6 ; Nr. 5, no. 6 (2005-10-26), S.799-819 |
| Datensatznummer |
250002877
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| Publikation (Nr.) |
 copernicus.org/nhess-5-799-2005.pdf |
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| Zusammenfassung |
| This paper is an extension of the single-phase cohesionless dry granular
avalanche model over curved and twisted channels proposed by Pudasaini
and Hutter (2003). It is a generalisation of the Savage and
Hutter (1989, 1991) equations based on simple channel topography to a
two-phase fluid-solid mixture of debris material. Important terms emerging
from the correct treatment of the kinematic and dynamic boundary condition,
and the variable basal topography are systematically taken into account. For
vanishing fluid contribution and torsion-free channel topography our new
model equations exactly degenerate to the previous Savage-Hutter model
equations while such a degeneration was not possible by the Iverson and
Denlinger (2001) model, which, in fact, also aimed to extend the Savage and
Hutter model. The model equations of this paper have been rigorously derived;
they include the effects of the curvature and torsion of the topography,
generally for arbitrarily curved and twisted channels of variable channel
width. The equations are put into a standard conservative form of partial
differential equations. From these one can easily infer the importance and
influence of the pore-fluid-pressure distribution in debris flow dynamics.
The solid-phase is modelled by applying a Coulomb dry friction law whereas
the fluid phase is assumed to be an incompressible Newtonian fluid. Input
parameters of the equations are the internal and bed friction angles of the
solid particles, the viscosity and volume fraction of the fluid, the total
mixture density and the pore pressure distribution of the fluid at the bed.
Given the bed topography and initial geometry and the initial velocity
profile of the debris mixture, the model equations are able to describe the
dynamics of the depth profile and bed parallel depth-averaged velocity
distribution from the initial position to the final deposit. A shock
capturing, total variation diminishing numerical scheme is implemented to
solve the highly non-linear equations. Simulation results present the
combined effects of curvature, torsion and pore pressure on the dynamics of
the flow over a general basal topography. These simulation results reveal new
physical insight of debris flows over such non-trivial topography. Model
equations are applied to laboratory avalanche and debris-flow-flume tests.
Very good agreement between the theory and experiments is established. |
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