Numerical modelling of water jet induced erosion in saturated sand

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The objective of this research proposal is to better understand the physical processes during the erosion of soils with a fluid jet, especially the erosion of saturated sand with a water jet. This includes the propagation of the water jet, the soil erosion process, the transient propagation of the erosion front up to the maximal erosion range, the transport of suspended soil particles and finally the sedimentation of the particles. To achieve this objective, a novel concept called “geometrically combined resolved-unresolved CFD-DEM” method for the numerical investigation of the jet grouting process will be developed. The idea behind this new technique is that the “erosion front” of the jet, where a detailed resolution is required, will be modelled with resolved CFD-DEM and the regions outside the “erosion front”, where the dynamics of fluid-particle interaction is much lower, unresolved CFD-DEM will be applied. This approach will ensure efficient modelling of a highly dynamic and large-scale process like water jetting at manageable computational costs and without compromising on the detail and accuracy where it is needed. Since the soil skeleton is dynamically moving, it becomes obvious that the transition of a soil particle from the unresolved to the resolved region (and vice versa) will need complex modelling algorithms. Further keeping in mind that the “erosion front” is moving in time, the need for a dynamic adaption of the “resolved erosion front” becomes clear. The numerical model development will be accompanied by experimental investigations to validate the numerical model. To reach the defined objectives a co-operation between Hamburg University of Technology/Germany and DCS Computing Linz/Austria is planned. DCS is developing the code CFDEM(R) coupling, which is used in the research project. This cooperation is covered by the D-A-CH agreement (DFG in Germany and FWF in Austria).