Prediction of morphology evolution under bridges through coupled CFD-DEM modelling

Abstract:

Bridge failures generated by scour processes is a well-known problem in engineering. Both the lack of knowledge of how these processes occur and evolve, and the increase in the frequency of extreme floods underpinned by climate change, continue to give us examples of this type of structural failure throughout the world.

In order to continue developing the understanding of scour processes on bridges, and in particular on scour around piers and abutments, this work will present an application of a novel numerical approach for the modelling of morphological evolution of the bed surface around an arched masonry bridge located in Ireland. The numerical modelling will comprise Computational Fluid Dynamics (CFD) coupled with Discrete Element Method (DEM) model to predict the gravel bed movements under extreme flood events.

A CFD model is built to represent the hydrodynamics of the river under the required flood conditions whilst the DEM techniques applied describe the movement of particles and its interaction with other particles and the model boundaries. Coupling these two modelling techniques permits represent the influence of flow over particles, mainly through drag and lift forces.

The river hydrodynamics and associated particles trajectories for several scenarios will be contrasted against experimental observations in a qualitative basis.

The implementation of coupled CFD-DEM models provides a very powerful tool for design and verification of key infrastructure with potential implementation on live monitoring.