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为将基于力源拟化边界思想的浸入边界法应用于工程结构空气绕流模拟,如桥梁结构,选定适用于刚性边界的浸入边界算法(Virtual Boundary Method),结合交错网格及时间分步法,重点借助双线性插值实现拉格朗日点与欧拉点之间的数据传递以形成物体边界。分析其浸入边界形成机理和模拟结果,逐次展开对静止方柱、圆柱绕流及有风攻角的方柱绕流的数值模拟,最后完成对桥梁断面的绕流模拟。研究结果表明:在Virtual Boundary算法模型作用下,物体边界形成仅需0.6s,且符合无滑移壁面边界设定;物体内部流体隔绝于外部流动,流动衰减,仅起到光滑函数作用;方柱、圆柱、有风攻角的方柱绕流在该算法模型下所得流动现象与气动力和过往文献相同;对于桥梁断面,升力系数随风攻角增大有显著提升,3°攻角下尾部流场产生扰动出现明显的流场非对称性,攻角的改变并不影响断面尾部的旋涡脱落频率。
In order to apply the immersed boundary method based on the idea of force source boundary to the simulation of air flow around engineering structures, such as bridge structure, the Virtual Boundary Method is selected for rigid boundary, combined with staggered grid and time step Method, focusing on the use of bilinear interpolation to achieve data transfer between the Lagrange point and Euler point to form the object boundary. The formation mechanism and simulation results of the immersed boundary are analyzed. Numerical simulation of flow around the square column with static square column, circular cylinder and windy attacking angle is carried out successively. Finally, the flow around the bridge section is simulated. The results show that the boundary of object is only 0.6s under the action of Virtual Boundary algorithm model, and it meets the boundary condition of no-slip wall. The fluid inside the object is isolated from the external flow, the flow attenuation, only play a smooth function; , The flow around the column and windy corner of the square column flow in the algorithm model is the same as the previous literature. For the bridge section, the lift coefficient increases significantly with the increase of wind attack angle, and the tail at 3 ° angle of attack The disturbance of flow field shows obvious asymmetry of flow field. The change of angle of attack does not affect the frequency of vortex shedding at the end of the section.