When multiphase flows are modeled numerically, complex geometrical and operational features of the experiments, such as the phase mixing section, are often not resolved in detail. Rather simplified boundary conditions are prescribed, which usually cause less irregular dynamics in the system than present in reality. In this paper, a perturbation that randomly disturbs the secondary components of the velocity vector at the inlet is proposed in order to capture the experimentally observed instabilities at the interface between the phases. This in particular enhances the formation of slugs in the pipe. Different amplitudes of the perturbation are investigated. One observes that, the higher the perturbation amplitude, the earlier the slugs occur. On the other hand, sufficiently far away from the inlet, the flow pattern shows the same dynamics for different perturbation amplitudes. Hence, no specific frequency is imposed by the prescribed perturbation. The simulation results are validated by comparison with liquid level data from a corresponding experiment.

当对多相流进行数值模拟时，实验的复杂几何和操作特征（例如相混合部分）通常无法详细解析。规定了相当简化的边界条件，这通常会导致系统中的不规则动态比实际情况少。在本文中，提出了一种随机扰动入口处速度矢量的二次分量的扰动，以捕获在相之间的界面处实验观察到的不稳定性。这尤其会促进管中段塞的形成。研究了扰动的不同幅度。可以观察到，扰动幅度越高，段塞出现得越早。另一方面，离入口足够远，对于不同的扰动幅度，流动模式显示相同的动力学。因此，规定的扰动没有强加特定的频率。通过与来自相应实验的液位数据进行比较来验证模拟结果。