Simulation of Erosion Phenomena Using Computational Fluid Dynamics Coupled with Mesh Morphing and Discrete Element Method

Abstract

Erosion is responsible for a tremendous economic loss in different parts of the world, particularly the US annually. Many dams in the world and the US are earth dams, which are susceptible to internal erosion due to their old ages. All around the world, about 46% of dams suffer a risk of internal erosion. In France, nearby 70 critical cases have already been detected (Monnet et al. 2012). In addition, vast distances of shores in the US are prevented from floods with levees, which can lose their functionality in surface erosion due to overtopping (Briaud et al. 2008). A large number of bridges can be in danger due to scour in floods. Scour has been the number one cause of bridge failure in the United States, with an average annual rate of 22 bridges collapsing or closed due to severe deformation (Briaud et al. 2014). These treats emphasize the importance of continuing research on erosion. Different researchers have proposed different test methods to quantify the magnitude of erosion due to water flow. Some other researchers utilized numerical methods to tackle erosion problems. Still, due to new advances in numerical methods and the necessity to apply these new methods in the study of erosion, more research is needed. This dissertation intends to utilize numerical approaches to model erosion tests and indicates the application of numerical simulation in erosion modeling. The first goal is to start modeling well-known erosion tests using mesh morphing technique (computational fluid dynamic (CFD) domain with erodible boundaries). By utilizing erosion function (EF), resulted from Erosion Function Apparatus (EFA) (Briaud et al. 2001), other erosion tests and even practical models of erosion can be modeled with this technique. Results of different erosion tests, including Borehole Erosion Test (BET) (Briaud et al. 2016), Hole Erosion Tests (HET) (Wan 2006, Wan 2004a, Wan 2004b), Jet Erosion Tests (JET) (Hanson 1990, Hanson 1991) have been compared with the results of numerical simulation with mesh morphing technique to verify the applicability of this method. The tests mentioned above are intended to be modeled with this new technique to extend the research from macro to micro by parallelizing CFD with the discrete element method (DEM) (CFD-DEM technique). One of the problems in soil erosion that needs to be investigated is the particles' incipient motion. Results of CFD-DEM simulation of EFA will be compared with the result of video analysis on EFA tests to investigate the incipient motion of particles in the erosion process. Accelerations, velocities, drag forces, and shear stresses extracted from the two approaches will be compared to study the incipient motion more precisely. Application of the two numerical approaches (Dynamic mesh technique and CFD-DEM) in practical problems is another goal, followed in this research. Scour and infilling in erosion are two practical applications that can be more investigated using these CFD techniques.