Numerical investigation of local scour around three adjacent piles with different arrangements under current

- A sediment scour model was adopted to describe the sediment transport process.
- The mechanism of local scour around three adjacent piles was investigated.
- Pile spacing has significant effects to the flow field and local scour around each pile.
- Local scour around each pile in three adjacent piles with different arrangements is different.

A set of three-dimensional numerical models is established to investigate the mechanisms of local scour around three adjacent piles with different arrangements under steady currents. The RANS equations, closed with a RNGk−ε turbulence model, are established for simulating the flow field around pile groups. A sediment scour model is adopted to estimate the motion of the sediment by predicting the erosion, advection, and deposition of the sediment. The simulation results of the bed elevation contours and the time evolution of scour depth around a single pile model are verified with the previous experimental results and show good agreement. Then, the effects of pile spacing for three adjacent piles with different arrangements on the flow field, bed elevation contours, and scour depth are discussed in detail. The results reveal that the dimensionless pile spacing has a significant effect on the flow field and local scour around the three adjacent piles. The scour hole patterns and scour depth around each pile with different arrangements are totally different.