Multi-phase flow is encountered in multiple industrial disciplines including oil and gas industry starting from the reservoirs, production tubes, well heads, separators and transportation systems comprehending risers & onshore/offshore transportation pipelines. The complex nature & instability of slug flow where pressure, temperature, velocities and flow rates oscillate lead to high fatigue loads on mechanical elements in pipelines. The prediction of the two-phase flow pattern inside pipelines is crucial in extending the life of the pipeline. This paper proposes the first numerical approach for predicting the vibration of a three-dimensional pipeline with an elbow due to two-phase flow using one-way fluid-structure interaction technique using the commercial software ANSYS. The unsteady Reynolds-averaged Navier-Stokes equations with three turbulent models are used to model the fluid domain. The finite element analysis is used to model the pipeline by using shell elements. The two-phase mixture superficial velocities inside the pipeline were identified by measuring the acceleration response of the surface of the pipe. Modal analysis is performed to check the variation of the pipeline natural frequency with the water content in the flow. The simulation results were validated with experimental data. Based on the simulation results, a numerical method for the measuring of the two-phase flow rates is proposed.
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