The two-phase flow past a square is a ubiquitous phenomenon widely encountered in industries and engineering, where the interaction of disparate phases coupled with the influence of the solid is rather complicated. In this context, the flow characteristics and the vortex field are investigated to reveal the mechanisms of the two-phase drag and the vortex variation. The lattice Boltzmann method (LBM) is utilized to study the multi-component two-phase flow. The computation implemented on the GPU is remarkably accelerated thanks to the natural parallelism of the LBM. The process of the two-phase flow past a square is thoroughly examined. The drag and lift forces, including the total force and the components caused by the dispersed phase and the continuous phase, respectively, are obtained, and their variation mechanisms are explained. Meanwhile, the vortex-identification approaches based on the Liutex as well as the traditional methods are compared. The relationship between the bubble breakup and coalescence processes and the extremums of different vortex identification variables is analyzed.

穿过正方形的两相流是在工业和工程中广泛遇到的普遍现象，其中不同相的相互作用以及固体的影响相当复杂。在这种情况下，研究了流动特性和涡流场，以揭示两相阻力和涡流变化的机理。格子Boltzmann方法（LBM）用于研究多组分两相流。由于LBM的自然并行性，GPU上实现的计算速度显着加快。彻底检查了通过一个正方形的两相流的过程。获得了分别包括分散相和连续相引起的总力和分力的阻力和升力，并说明了它们的变化机理。与此同时，比较了基于Liutex的涡旋识别方法和传统方法。分析了气泡破裂和聚结过程以及不同涡旋识别变量的极值之间的关系。