| Journal: | Journal of the Brazilian Society of Mechanical Sciences |
| Database: | PERIÓDICA |
| System number: | 000312030 |
| ISSN: | 0100-7386 |
| Authors: | Silvestrini, Jorge H1 |
| Institutions: | 1Universidade Federal do Rio Grande do Sul, Departamento de Matematica Pura e Aplicada, Porto Alegre, Rio Grande do Sul. Brasil |
| Year: | 2000 |
| Volumen: | 22 |
| Number: | 1 |
| Pages: | 53-67 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Analítico |
| English abstract | Coherent vortices in turbulent mixing layers are investigated by means of Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES). Subgrid-scale models defined in spectral and physical spaces are reviewed. The new "spectral-dynamic viscosity model", that allows to account for non-developed turbulence in the subgrid-scales, is discussed. Pseudo-spectral methods, combined with sixth-order compact finite differences schemes (when periodic boundary conditions cannot be established), are used to solve the Navier- Stokes equations. Simulations in temporal and spatial mixing layers show two types of pairing of primary Kelvin-Helmholtz (KH) vortices depending on initial conditions (or upstream conditions): quasi-2D and helical pairings. In both cases, secondary streamwise vortices are stretched in between the KH vortices at an angle of 45° with the horizontal plane. These streamwise vortices are not only identified in the early transitional stage of the mixing layer but also in self-similar turbulence conditions. The Re dependence of the "diameter" of these vortices is analyzed. Results obtained in spatial growing mixing layers show some evidences of pairing of secondary vortices; after a pairing of the primary Kelvin-Helmholtz (KH) vortices, the streamwise vortices are less numerous and their diameter has increased than before the pairing of KH vortices |
| Disciplines: | Física y astronomía, Ciencias de la computación |
| Keyword: | Dinámica de fluidos, Vórtices coherentes, Capa de mezcla, Simulación numérica, Simulación Large Eddy, Subredes |
| Keyword: | Physics and astronomy, Computer science, Fluid dynamics, Coherent vortices, Mixing layers, Numerical simulation, Large Eddy simulation, Subgrids |
| Full text: | Texto completo (Ver HTML) |
