Study on the Hydrodynamic Evolution Mechanism and Drift Flow Patterns of Pipeline Gas-Liquid Flow

The hydrodynamic characteristic of the multiphase mixed-transport pipeline is essential to guarantee safe and sustainable oil-gas transport when extracting offshore oil and gas resources. The gas-liquid two-phase transport phenomena lead to unstable flow, which significantly impacts pipeline deformation and can cause damage to the pipeline system. The formation mechanism of the mixed-transport pipeline slug flow faces significant challenges. This paper studies the formation mechanism of two-phase slug flows in mixed-transport pipelines with multiple inlet structures. A VOF-based gas-liquid slug flow mechanical model with multiple inlets is set up. With the volumetric force source term modifying strategy, the formation mechanism and flow patterns of slug flows are obtained. The research results show that the presented strategy and optimization design method can effectively simulate the formation and evolution trends of gas-liquid slug flows. Due to the convective shock process in the eight branch pipes, a bias flow phenomenon exists in the initial state and causes flow patterns to be unsteady. The gas-liquid mixture becomes relatively uniform after the flow field stabilizes. The design of the bent pipe structure results in an unbalanced flow velocity distribution and turbulence viscosity on both sides, presenting a banded distribution characteristic. The bend structure can reduce the bias phenomenon and improve sustainable transport stability. These findings provide theoretical guidance for fluid dynamics research in offshore oil and gas and chemical processes, and also offer technical support for mixed-transport pipeline sustainability transport and optimization design of channel structures.