Environmental effects on erosion characteristics of cohesionless particles through jet erosion test and CFD-DEM simulation

This paper investigates the erosion characteristics of different cohesionless particles under jet impinging flow conditions with varying fluid temperatures and salinities. A series of jet flow tests was conducted on cohesionless particle beds, and a corresponding CFD-DEM model with a realizable k-ε turbulence component has been developed to further evaluate the flow and particle-scale motion. Comparisons between the standard and realizable k-ε turbulence models show the realizable k-ε turbulence model predicts a converging jet flow more consistent with the experimental observations, and the simulated scour process replicates the experiments well. The accurate determination of critical shear stress from jet erosion tests is affected by the turbulence of water flow, scour hole morphology, temperature, and salinity, which were generally ignored in previous data interpretations. An environmental correction factor based on the Reynolds number has been proposed to solve this issue. With this corrected approach, it is found the fluid temperature and salinity do not affect the interpretation of critical shear stress due to soil’s intrinsic property, while the temperature affects the evolving rate of scour hole and the erodibility coefficient. The CFD-DEM analyses indicate that the changes of fluid density and dynamic viscosity are the fundamental reasons for these phenomena. A low-temperature and saline fluid possesses a high fluid density and dynamic viscosity, which eventually enhances the initiation, suspension, and transport of various particles. We suggest the environmental variables should be reported in the jet erosion test.