Modelling of Hydraulics and Morphology in Mountain Rivers

摘要

This analysis includes the applicability of simplified models, the mathematicalstability in case of graded sediment and the behavior of discontinuous flows at mobile beds. For test cases with strongly unsteady and non-uniform conditions of flow and values of the Froude number near unity, the quasi-steady flow assumption appears to be possible but not efficient, whereas the quasi-uniform flow assumption is found to be efficient but erroneous. In case of graded sediment and for high values of the Froude number, the mathematical stability of the model reduces for certain conditions. Some stabilizing options have been analyzed. The behavior of discontinuous flows such as hydraulic jumps at a mobile bed can be analyzed with shock relations and entropy condition. If the latter are satisfied, no conflict of information-transfer develops and within the limitations of the model, the discontinuous solution can be considered physically realistic.