Numerical Study of Particle Dispersion Phenomena in Turbulent Flows

  • 林 建宏

Student thesis: Doctoral Thesis

Abstract

Particle-laden flows widely appear in many engineering practices and physical phenomena Since both dispersed phase and carrier fluid have their own statistical natures of turbulence numerical simulations of particle-laden flows are very difficult to reliably and accurately predict An Eulerian-Lagrangian approach in which the carrier-fluid flow field is solved with a low-Reynolds-number turbulence model while the deterministic Lagrangian method together with binary-collision hard- sphere model is applied for the solution of particle motion Effects of inter-particle collisions and particle-wall collisions under different extents of wall roughness on particle dispersion are addressed in this thesis In the first part of this study a cost-effective searching collision pairs among particles algorithm which can be suitable for unstructured meshes system and easy to parallelize is developed The results show that the values of in the calculations using the range from to can provide a higher computational efficiency in the Lagrangian particles tracking algorithm A quantitative parametric study of the physical mechanisms and conditions which might affect the particles’ dispersion including the turbulence dispersion inter-particle collisions rough-wall effects on the particle-wall collisions and particles’ inlet conditions are also discussed The results show that the inter-particle collisions can not be ignored under the conditions of The influence of wall roughness on particle-wall collisions should also be able taken into account particularly for large particles The simulation results also found that only particles with Stokes numbers less than unity can be dispersed into the corner recirculation region in the backward-facing step flow
Date of Award2015 Jul 13
Original languageEnglish
SupervisorKeh-Chin Chang (Supervisor)

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