E-Thesis 159 views 121 downloads
The characteristic based split (CBS) scheme for laminar and turbulent incompressible flow simulations. / Chun-Bin Liu
Swansea University Author: Chun-Bin Liu
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In this thesis, the matrix free Characteristic Based SpHt (CBS) scheme based on an artificial compressibility (AC) method and the semi-implicit CBS scheme are presented for laminar and turbulent incompressible flows. Numerical simulations of steady and unsteady state incompressible flow problems hav...
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In this thesis, the matrix free Characteristic Based SpHt (CBS) scheme based on an artificial compressibility (AC) method and the semi-implicit CBS scheme are presented for laminar and turbulent incompressible flows. Numerical simulations of steady and unsteady state incompressible flow problems have been carried out on structured and unstructured meshes of linear triangular and tetrahedral elements. The standard Galerkin method was used for spatial discretization of the governing equations in their semi-discrete CBS form. Four different Reynolds average Navier-Stokes (RANS) turbulence models have been studied in detail. They are the one-equation linear kappa-l model of Wolfshtein, the one-equation Spalart-Allmaras model, the two-equation linear kappa-epsilon model with two different low Reynolds number treatments (Lam-Bremhorst damping functions and Fan- Lakshminarayana-Barnett damping functions), and the two-equation nonlinear near-wall kappa-epsilon model with Kimura-Hosoda's parameters. The results of standard steady flow in a channel, inside a lid-driven cavity, over a backward facing step, around a stationary sphere and through an upper human airway are adequately predicted. In addition to steady state flow problems, unsteady Reynolds-averaged Navier-Stokes (URANS) model was employed to solve vortex shedding behind a circular cylinder using a dual-time stepping technique. The two- and three-dimensional results presented show that both the CBS-AC matrix free procedure and semi-implicit CBS formulation are accurate and efficient.
Mechanical engineering.;Fluid mechanics.
Faculty of Science and Engineering