Numerical modelling of water jet induced erosion in saturated sand

这项研究的目的是为了更好地了解物理过程中的土壤与流体射流的侵蚀，特别是饱和砂与水射流的侵蚀。这包括水射流的传播、土壤侵蚀过程、侵蚀前沿到最大侵蚀范围的瞬时传播、悬浮土壤颗粒的运输以及最终颗粒的沉降。为了实现这一目标，一个新的概念，称为“几何结合解析-未解析CFD-DEM”方法的喷射灌浆过程的数值研究将开发。这种新技术背后的想法是，射流的“侵蚀前沿”，需要详细的分辨率，将与解决CFD-DEM和“侵蚀前沿”以外的区域，其中流体-颗粒相互作用的动力学低得多，未解决的CFD-DEM将被应用。这种方法将确保以可管理的计算成本对高度动态和大规模的过程（如喷水）进行有效建模，并且不会在需要时影响细节和准确性。由于土壤骨架是动态移动的，因此很明显，土壤颗粒从未解析区域过渡到解析区域（反之亦然）将需要复杂的建模算法。进一步牢记“侵蚀前沿”是随时间移动的，因此，对“已解决的侵蚀前沿”进行动态调整的必要性变得很明显。数值模型的开发将伴随着实验研究，以验证数值模型。为了实现既定目标，汉堡理工大学/德国和DCS计算林茨/奥地利之间的合作计划。DCS正在开发用于研究项目的代码CFDEM（R）耦合。这一合作由D-A-CH协议（德国的DFG和奥地利的FWF）涵盖。

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).