Efficient Numerical Methods for Waves in One-Dimensional Two-Phase Pipe Flows
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This thesis is aimed at improving simulation efficiency for stratified-wavy gasliquid flows. Towards this goad, the simpler nature of incompressible two-phase flows is utilized for predicting hydraulic wave dynamics, both through theoretical analysis and numerical simulation. Numerical methods proposed for the incompressible two-fluid model include a hybridization of a finite volume method with analytical roll-wave profile solutions, a Method of Characteristics and finite volume hybridizations thereof, and a linearized Riemann solver (Roe scheme.) Theoretical analyses based on the same model further the understanding of Kelvin- Helmholtz stability in stratified pipe flows and provide a comprehensive account of how the flow stability predictions of numerical simulators depend on model discretization. Kelvin-Helmholtz/von Neumann analysis is shown to be a valuable support tool for choosing numerical scheme and simulation parameters. Finally, a dual grid scheme is proposed which enables us to extend the computational benefits of incompressible flow models to compressible systems. The dual grid scheme effectively decouples the length scales and numerical CFL restrictions of hydraulic (incompressible) waves from that of acoustic (compressibility) waves. Efficiency is observed to be improved by several orders of magnitude for a wide range of simulation cases.
Has partsPaper 1: Akselsen, Andreas Holm; Nydal, Ole Jørgen. Applying Multiple Grids to a Multi-Field Model - The Resolution Requirements of Individual Fields in the Two-Fluid Model for 1D Pipe Flow. Journal of Dispersion Science and Technology 2015 ;Volum 36.(10) s. 1378-1387 http://dx.doi.org/10.1080/01932691.2014.987783
Paper 2: A METHOD OF CHAINED ANALYTICAL WAVE STRUCTURES FOR LARGE-SCALE STRATIFIED TWO-PHASE PIPE FLOWS - Proceedings of The VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2016) © 2016 Computational Methods in Structural Dynamics & Earthquake Engineering. All Rights Reserved.
Paper 3: Characteristic Methods and Roe’s Method for the Incompressible Two-Fluid Model for Stratified Pipe Flow
Paper 4: The Stability of Roll-Waves in Two-Phase Pipe Flow
Paper 5: The Kelvin-Helmholtz/von Neumann Stability of Discrete Representations of the Two-Fluid Model for Stratified Two-Phase Flow
Paper 6: A Dual Grid Method for the Compressible Two-Fluid Model which Combines Robust Flux Splitting Methodology with High-Resolution Capturing of Incompressible Dynamics