Abstract: In order to study the dynamic effects of water flow on bridge pile foundation in deep water, this paper analyzed the flow characteristics of four cylinder pile by using the Reynolds averaging method based on the ANSYS/FLUENT numerical simulation software, and studied the flow field characteristics of four cylinder pile under seven different angles of incoming flow and three typical spacing ratios, the drag coefficient of each pile and the distribution of shear stress on the bed surface around the pile. The results show that both the angle of incoming flow and the spacing ratio have a strong influence on the flow characteristics of the four cylinder pile. With the angle of incoming flow increasing from $ 0^{\circ} $ to $ 45^{\circ} $, the shear stress distribution mode of the downstream pile bed surface gradually changes from the shielded state to the separated flow impact state. When the spacing ratio is 1.0, the critical shielding angle is $ 5^{\circ} $. When the spacing ratio is 1.5 or 2.0, and the angle of incoming flow is between $ 20^{\circ} $ and $ 30^{\circ} $, the drag coefficient of each pile is in the range of $ 1.0 \pm 0.2 $, and the shielding effect is minimal.
Keywords: Reynolds averaging method; angle of incoming flow; spacing ratio; four cylinder pile; numerical simulation