【摘要】 为研究近床面结构物周围的局部冲刷问题,该文基于N-S方程和有限体积法,在FLUENT中进行二次开发,建立了局部冲刷问题的三维通用计算模型。模型通过标准k-?模型计算结构物周围的流场,并使用FLUENT软件中的自定义函数功能,提取床面网格信息与床面剪应力。据此来计算一段时间内的推移质输沙率,进而得到床面节点的高程变化。最后,再通过动网格技术,更新床面网格形状,完成一个时间步长的床面变形计算。该文模拟了水平管道周围冲刷与圆球附近的冲刷,计算结果与实验结果吻合良好,验证了模型的准确性。同时,该研究讨论了流动与冲刷时间步长的选取对计算效率与计算精度的影响。更多还原

【Abstract】 A numerical model has been developed for predicting the flow and local scour around offshore structures. The commercial software FLUENT is used as a flow solver, which solves the unsteady Reynolds-averaged Navier-Stokes equations with standard k-? turbulence closure. The bedload sediment transport equations are then solved using the finite difference method through user-defined-functions(UDFs), which enable users to interfere the computaiontal procedures in FLUENT. The change in the bed level is calculated from the continuity equation of sediment transport, and the dynamic mesh method is used to update the bed positions during the simulation. An efficient time-marching algorithm is adopted to accelerate the computation. Two examples are presented to verify the newly-developed model. One is the vertical two-dimensional scour around a near-bed horizontal pipeline, and the other is the three-dimensional scour around a near-bed sphere. The model predictions are found to agree well with experimental results in both cases.更多还原