Numerical simulation of open channel flow influenced by pile piers

A 2-D numerical model for open channel flow influenced by pile piers is set up,considering the piers as impermeable area.The method of gradually refined triangular meshes is used to simulate the shape of piles with high precision.Based on this model,the water level and velocity of water flow, which are influenced by single line piers,are calculated,and the differences in the influence of square piles and circular piles on water flow are discussed.Furthermore,the effect of Manning's roughness and eddy viscosity on the upstream backwater is analyzed.The result shows that the variation of water level and velocity caused by piles are different along the vertical-section and cross-section,and the variation of water level presents a "wave-like" distribution along the cross-section.In general,the water level rises and the velocity decreases in the upper reaches,while in the lower reaches the water level falls and the velocity increases.It can also be concluded that square piers have greater influence on water flow than circular ones,and the backwater upstream is more sensitive to the eddy viscosity than to the Manning's roughness.