Two-flow model for piping erosion based on liquid-solid coupling

LIANG Yue(梁越)^{1, 2}, WANG Jun-jie(王俊杰)^{1, 2}, LIU Ming-wei(刘明维)^{1, 2}

(1. National Engineering Research Center for Inland Waterway Regulation (Chongqing Jiaotong University),
Chongqing 400074, China;
2. Key Laboratory of Hydraulic & Waterway Engineering of the Ministry of Education
(Chongqing Jiaotong University), Chongqing 400074, China)

Abstract:Previous studies have indicated that piping erosion greatly threatens the safe operation of various hydraulic structures. However, few mathematical models are available to perfectly describe the erosion process due to the complexity of piping. The focus of the present work is to propose a new fluid-solid coupling model to eliminate the shortcomings of existing work. A “pseudo-liquid” assumption is suggested to simulate the particle movement in the erosion process. Then, based on the mass and momentum conservations of the moving particles and flowing water, a new two-flow model is established by using the continuity equations and motion equations. In the model, the erosion rate of soil is determined with a particle erosion law derived from tests results of STERPI. And ERGUN’s empirical equation is used to determine the interaction forces between the liquid and the solid. A numerical approach is proposed to solve the model with the finite volume method and SIMPLE algorithm. The new model is validated with the tests results of STERPI. And the soil erosion principles in piping are also explored.

Key words:piping erosion; two-flow model; liquid-solid interaction; erosion rate; drag force