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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Numerical modeling of geomorphic processes in the presence of slope failures
Numerical modeling of geomorphic processes in the presence of slope failures
Unsteady flows in rivers with steep bedforms or banks are not only governed by flow-driven sediment transport but also by
collapse mechanisms. As a consequence, slope failure mechanisms have been recently included in morphodynamic
models in order to improve their descriptive capabilities.
The objective of the paper is to test the performances of a two-phase model which includes a geo-failure operator through
its application to some synthetic test cases. The resulting mathematical model is numerically solved through a mixed Cell-
Centered and Node-Centered Finite-Volume discretization over unstructured triangular meshes. The two-phase model
accounts for variable bed-load sediment concentration and for inter-particle collisional stresses. The geo-failure operator
performs in a way that when in the cell the bed slope exceeds a critical angle, the corresponding bed material and pore
water becomes available to flow, thus following the two-phase flow dynamics. The algorithm also permits the failure to
propagate from the single cell to the entire domain, preserving both the continuity of the bottom surface and the mass
The numerical simulations of some significant test-cases enlighten the effectiveness of the proposed model. The selected
examples simulate key-conditions in which the slope failure and/or the interactions between phases have to be
mandatorily accounted for. In all the presented tests, the initial slope, connecting two horizontal reaches, exceeds the
material repose angle in saturated conditions. In detail, the following scenarios have been simulated: a) slope partially or
completely submerged by still water (where the submerged part is not in equilibrium in the initial condition); b) slope
invested by a dam-break wave eventually overtopping the upper horizontal part; c) filling of a reservoir by a constant
discharge, which gradually submerges the barraging slope.
Simulation results prove the reasonable capability of the considered model to deal with all these different conditions,
reproducing the main features of the complex interaction between sediment and water.
File Size : 537,962 bytes
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Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 20/08/2015
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