Numerical investigation of impact of pile space on flow around two vertical cylindrical piles

The flow around two vertical cylindrical piles exposed to a steady current is studied numerically by a three-dimensional hydrodynamic model, which is closured with a k-epsilon turbulence model. This model is firstly validated by experimental data obtained from a laboratory experiment for a steady flow through a circular pile. Then this validated model is used to study flow pattern around two cylindrical piles. Finally, four key physical factors of the size of the horseshoe vortex and lee wake vortex, the maximum current velocity and bottom shear stress are analyzed under the different pile spaces. The main conclusions are: i) the size of the horseshoe vortex increases with the increase of the two pile space, while the size of the lee wake vortex changes slightly; ii) the maximum current velocity and the maximum bottom shear stress decrease with the increase of two pile space, and reach steady after the two pile space larger than six times of cylindrical pile diameter.