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Numerical investigation of a single gas structure impacting a cylinder, first steps towards the up-scaling
William Benguigui, Enrico Deri, Jérôme Laviéville, Stéphane Mimouni, Elisabeth Longatte

Last modified: 2018-05-04

Abstract


Interactions between a cylindrical structure and two-phase flows are a major concern for industrial applications especially in heat exchangers where cross-flows may occur. In order to understand the vibrations induced by a two-phase flow, experiments were conducted in the past with a single tube for various two-phase flow regimes. Since numerical simulation allows now one to handle two-phase flows, it is possible to carry out complex investigations at the finest scale: the bubble.
Using a finite-volume CFD software dedicated to multi-phase flow based on a two-fluid approach, the authors study the impact of a single bubble in a fluid at rest on a cylinder with fully refined meshes. Flow being laminar, no turbulence model is applied.
Firstly, the rise of  single bubbles in the fluid at rest is correctly reproduced according to the experiments of Bhaga&Weber (1981). Then, we study the interaction between the bubbles and a cylindrical structure with three mesh-refinements. Since the gas-liquid interface is tracked, the break-up of different bubbles and its influence on the cylinder are studied, in order to have get a more microscopic information to characterize two-phase flows across tube arrays. Finally, the authors give propose some conclusions on the importance of small-scale analysis to understand macroscopic industrial phenomena.


Keywords


two-phase, computational fluid dynamics, microscopic scale

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