Simulations of Sediment Dynamics in Supercritical, Free-Surface Flows

• Applicants: Harald Köstler; Professor Dr.-Ing. Bernhard Vowinckel
• Subject Area: Fluid Mechanics ; Geotechnics, Hydraulic Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569695058

This research proposal aims to advance our understanding of antidune dynamics in supercritical flows, with a focus to conduct a systematic campaign of numerical simulations with well controlled boundary conditions. Antidunes, short-wave periodic disturbances that occur in phase with the water surface, are crucial features in the study of flow dynamics in open channels, alluvial rivers, and estuaries. Despite their significance, the understanding of antidunes remains limited, especially in comparison to their subcritical counterparts like dunes. The proposed research will address identified knowledge gaps related to the absence of comprehensive experimental datasets describing flow-sediment interactions when antidunes are present. Special attention will be given to the shape, symmetry, and spatial variability of antidunes in supercritical flows. The research will employ state-of-the-art particle-resolving numerical simulations to obtain highly-resolved data that cannot be obtained in experimental setups. These simulations, which consider the motion and flow around individual particles, have shown promise in replicating experimental conditions and accurately simulating the development of upstream migrating antidunes. The data therefore detailed insights into the mechanics of antidune movement, including particle transport modes and the influence of flow conditions on sediment fluxes. The study will also explore the impact of bed permeability and subsurface flow on antidune morphodynamics, providing insights into how these factors influence flow structures over the bed in supercritical conditions. The research outcomes will contribute to a more comprehensive understanding of antidunes, their formation, and their implications for sediment transport in steep alluvial streams. This research proposal aims to provide a holistic view of antidune dynamics, contributing to the development of accurate models for predicting bedform characteristics under supercritical flow conditions. The findings will not only enhance our fundamental knowledge of geomorphic processes but also have practical applications in flood management, dam reservoir flushing, and the preservation of stratigraphic records.

• DFG Programme: Research Grants