In order to explore the applicability of different implementation methods for periodic boundary conditions involved in the open-source computational fluid dynamics software,by the name of OpenFOAM,numerical simulations on the Poiseuille flow in a circular pipe were performed,using mapped,cyclicAMI and cyclic fan boundary conditions,respectively.The numerically obtained velocity and pressure profiles were analyzed.The results show that the velocity profiles obtained under the three boundary conditions are in agreement with the analytical solution.Specifically,the results under the mapped and cyclicAMI boundary conditions,which are very close to each other,agree better with the analytical solution.The pressure profile obtained under the mapped boundary condition is in good agreement with the analytical solution,whereas there are large pressure gradients at the inlet and outlet of the simulation domain when the cyclic fan boundary condition is adopted.Moreover,the pressure along the pipe axis is always zero under the cyclicAMI boundary condition.On this basis,the sensitivity of the numerical simulation results to the computational cell was examined.It is found that as the cell number along the pipe diameter increases,the computational accuracy of the velocity increases rapidly and then becomes stable.The increase of the number of boundary layers can effectively improve the computational accuracy of the velocity near the wall.Furthermore,more than 16 cells along the diameter and not less than 3 boundary layers are necessary for numerical simulations.%为探究开源计算流体力学软件OpenFOAM中不同周期性边界条件处理方法的适用性,针对圆管内泊肃叶流动,分别在mapped,cyclicAMI,cyclic fan边界条件下开展数值模拟,对模拟得到的速度分布和压力分布进行分析.结果表明:3种边界条件设置下,数值模拟得到的速度分布均与解析解吻合,其中mapped和cyclicAMI边界条件下的数值解非常接近,且与解析解吻合更好;采用mapped边界能够得到与解析解符合的压力场,采用cyclic fan边界时在模拟区域进、出口存在很大的压力梯度,采用cyclicAMI边界得到的压力则恒为0.基于此,探讨了mapped边界条件下,数值模拟结果对计算网格的敏感性.研究发现:随着径向网格数目的增加,速度的计算精度先迅速提高而后趋于稳定;边界层层数的增加能够有效提高近壁区速度的计算精度;数值模拟时径向网格数目采用 16个以上为宜,边界层层数不宜少于3层.
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