Numerical simulation is a very useful tool for the prediction of physical quantities in two-phase flows. One important application is the study of oil-gas flows in pipelines, which is necessary for the proper selection of the equipment connected to the line during the pipeline design stage and also during the pipeline operation stage. The understanding of the phenomena present in this type of flow is more crucial under the occurrence of undesired effects in the duct, such as hydrate formation, fluid leakage, PIG passage, and valve shutdown. An efficient manner to model two-phase flows in long pipelines regarding a compromise between numerical accuracy and cost is the use of a one-dimensional two-fluid model, discretized with an appropriate numerical method. A two-fluid model consists of a system of non-linear partial differential equations that represent the mass, momentum and energy conservation principles, written for each phase. Depending on the two-fluid model employed, the system of equations may lose hyperbolicity and render the initial-boundary-value problem ill-posed. This paper uses an unconditionally hyperbolic two-fluid model for solving two-phase flows in pipelines in order to guarantee that the solution presents physical consistency. The mathematical model here referred to as the 5E2P (five equations and two pressures) comprises two equations of continuity and two momentum conservation equations, one for each phase, and one equation for the transport of the volume fraction. A priori this model considers two distinct pressures, one for each phase, and correlates them through a pressure relaxation procedure. This paper presents simulation cases for stratified two-phase flows in horizontal pipelines solved with the 5E2P coupled with the flux corrected transport method. The objective is to evaluate the numerical model capacity to adequately describe the velocities, pressures and volume fraction distributions along the duct.
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机译：数值模拟是一种非常有用的工具，用于预测两相流中的物理量。 One important application is the study of oil-gas flows in pipelines, which is necessary for the proper selection of the equipment connected to the line during the pipeline design stage and also during the pipeline operation stage.在这种类型流中存在的现象的理解在导管中的不期望的影响发生，例如水合物形成，流体泄漏，猪通道和阀门关闭。在长管道中模拟两相流的有效方式关于数值精度和成本之间的折衷是使用一维两种流体模型，以适当的数值方法离散化。双流体模型由非线性偏微分方程的系统组成，代表为每个阶段编写的质量，动量和节能原理。根据所用的双流体模型，方程式可能丢失双曲性并使初始边界值问题呈现不良。本文采用无条件的双曲线双流体模型，用于求解管道中的两相流动，以保证该解决方案呈现出物理一致性。这里称为5E2P（五个方程和两个压力）的数学模型包括连续性的两个方程和两个动量保守方程，一个用于每个相的一个，以及一个方程，用于传输体积分数。该模型的先验模型考虑两个用于每个相的不同压力，并通过压力松弛程序将它们与它们相关联。本文介绍了用5E2P耦合的水平管道中的分层两相流量的模拟案例，与磁通校正的传输方法。目的是评估数值模型能力，以充分描述沿着管道的速度，压力和体积分布。
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