Maio 2014 vol. 1 num. 1 - 10th World Congress on Computational Mechanics
Full Article - Open Access.
ADAPTIVE NUMERICAL SIMULATIONS OF A TURBULENT JET
This work is concerned with assessing the performance of a numerical method, which combines an adaptive mesh refinement technique, an implicit-explicit time stepping strategy, and a linear multilevel-multigrid methodology, when applied to a challenging reallife problem: a three-dimensional turbulent jet flow. Typically, whenever a moving fluid emerges from a narrow opening into an otherwise quiescent fluid, shear is created between the entering and the ambient fluids, causing fluid instabilities, turbulence, and mixing at downstream. Turbulent jets represent an important class of fluid flow phenomena which occurs in many instances both in environmental and in industrial applications such as waste water discharges into rivers, plumes from smokestacks, and flames on combustion nozzles. Mathematically, the fluid dynamics is modeled by the non-steady Navier-Stokes equations for a three-dimensional incompressible flow whose material properties vary. The turbulence modeling is given by the large eddy simulation approach for which a careful selection of the Smagorinsky constant is performed. To resolve accurately and efficiently sharp gradients, vorticity shedding, and localized small length scale flow features (e.g. the ones present in high turbulence regions), dynamic adaptive mesh refinements are employed which form a level hierarchy composed by a set of nested, Cartesian grid patches (block-structured grid). That spatial adaptation is used in conjunction with a variable time step, linearly implicit time integration scheme, based on a semi backward difference formula (SBDF), especially designed to work with the non-linear diffusive term arising from the turbulent viscosity. The NS solver is based on an increment-pressure projection method. Information on how often the mesh adapts itself, on the number of computational cells in use, on the stability and size of the integration time step, and on the behavior of the multilevel-multigrid solvers is collected, showing the performance and testing the capabilities of the overall methodology.
Palavras-chave: Adaptive mesh refinement, Implicit-explicit scheme, Large eddy simulation, Multilevel- multigrid method, Projection method.,
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Calegari, P. C.; Roma, A. M.; Filho, G. C. K.; Santos, L. C. C.; "ADAPTIVE NUMERICAL SIMULATIONS OF A TURBULENT JET", p. 5008-5017 . In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1].
São Paulo: Blucher,
ISSN 2358-0828, DOI 10.5151/meceng-wccm2012-20190
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