A 7-field Lagrangian slug capturing and slug tracking model with higher order methods
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In this thesis, a 7-field Lagrangian slug capturing and slug tracking model with higher order methods and an adaptive grid is investigated for predicting the behaviour of two-phase gasliquid flow in multiphase flow pipelines. The model is capable of simulating both compressible and incompressible slugs, and pigs. The model has the possibility to simulate gas-liquid flow, including a liquid droplet field in the gas and entrained gas in the liquid. Walls consisting of multiple layers of different materials can be added to the pipes, and the energy equations for both the pipe walls and the fluids are solved. The mass, momentum and energy equations are solved in an iterative manner. Several additional tools and features have also been developed, like a steady state solver for the velocity, holdup, pressure and temperature, a unit-cell model which can be used as a standalone tool or as a sub-grid model in the dynamic model, fully period boundary conditions, curved pipe geometry, usage of tabulated PVT-files, and modelling of interfacial mass transfer. Higher order schemes are available for both spatial and temporal discretization. Different details in the two-fluid model have also been investigated, amongst other how to handle changes in the pipe cross-sectional area correctly for the border movement and level gradient. It is also shown how the upwind velocity must be modified by scaling factors to obtain the correct Bernoulli effect in the case of incompressible flow. The work resulted in four papers. In Paper 1 the model was tested against large scale experimental data, and was shown to give good predictions of the slugging periods after including a liquid droplet field and including the separator in the simulations. In Paper 3 the slug capturing capabilities of the model are tested against experimental data from a medium scale flow loop, related to a project investigating cleaning of water distribution systems by use of slug flow. Paper 2 investigate the ability of higher order spatial and temporal schemes in detecting ill-posedness in the two-fluid model. Paper 4 is a continuation of Paper 2, and analyse the accuracy, stability and damping properties of different time integration schemes for the two-fluid model.
Består avPaper 1: Smith, Ivar Eskerud; Nydal, Ole Jørgen. The effect of boundary conditions and droplet entrainment on severe slugging using a Lagrangian slug tracking model. International Journal of Multiphase Flow 2016 ;Volum 85. s. 245-257 https://doi.org/10.1016/j.ijmultiphaseflow.2016.06.014
Paper 2: Hendrix, Maurice HW; Smith, Ivar Eskerud; van Zwieten, Joost S.B.; Sanderse, Benjamin. Comparison of numerical methods for slug capturing with the two-fluid model - ICMF-2016 – 9th International Conference on Multiphase Flow
Paper 3: Pourcel,Florent; Smith, Ivar Eskerud; Duchesne, Sophie. Slug flow simulation, a way to improve air scouring of water mains? Procedia Engineering Volume 186, 2017, Pages 601-608 https://doi.org/10.1016/j.proeng.2017.03.276 Under a Creative Commons license Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Paper 4: Sanderse, Benjamin; Smith, Ivar Eskerud; Hendrix, Maurice HW. Analysis of time integration methods for the compressible two-fluid model for pipe flow simulations. International Journal of Multiphase Flow 2017 ;Volum 95. s. 155-174 https://doi.org/10.1016/j.ijmultiphaseflow.2017.05.002