H&TECH

The flow around a cylinder at high Reynolds numbers is turbulence that can be compressed. Turbulence is an extraordinarily complex three-dimensional flow, which is unsteady, erratic and composed of eddies. The characteristic of turbulence is the fluctuation of physical quantity generated by a random motion of vortex at different scales [8] performed the DES of flow around a cylinder in a uniform cross-flow in the subcritical(laminar-separation) and postcritical(turbulent-separation) flow regimes. The results were very similar to those of the experiment and also with LES, especially at a subcritical Reynolds number of 5.0 × 10 4 . Gu et al. [10] used the DES method based on the SST two-equation turbulence model to stimulate the incompressible viscous flow around a cylinder. They proved that the DES method is valid and reliable to simulate the flow around a cylinder with a low or higher subcritical Reynolds number. Xu et al. ABSTRACT The combined section structure has been extensively used in engineering practice. However, there has been little research on the flow around a combined structure. Based on this situation, the numerical simulations of the flow around a combined pier with Reynolds numbers in the range of 1.0×10 6~2 .76×10 6 are performed. The time histories of lift coefficient and drag coefficient of three combined piers with different types (such as combined cylindrical pier, truncated-cone pier, combined truncated-cone pier) in different water depths are analyzed based on detached eddy simulation (DES) by using the fluid dynamics software FLUENT. The results show that the lift coefficient and drag coefficient between the combined cylindrical pier and the truncated-cone pier are basically the same under the condition of the same water depth. When the water depth is 3.0m, the drag coefficient of the combined truncated-cone pier is smaller than that of the combined cylindrical pier and truncated-cone pier. When the water depth is 4.0m or 5.0m, the drag coefficient of the combined truncated-cone pier is greater than that of the combined cylindrical pier and the truncated-cone pier. The form of the cross section of the submerged portion of the combined pier has a significant influence on the average drag coefficient under the condition of a different water depth