| dc.creator |
Silvestrini Jorge H. |
|
| dc.date |
2000 |
|
| dc.date.accessioned |
2013-05-30T11:22:21Z |
|
| dc.date.available |
2013-05-30T11:22:21Z |
|
| dc.date.issued |
2013-05-30 |
|
| dc.identifier |
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-73862000000100005 |
|
| dc.identifier |
http://www.doaj.org/doaj?func=openurl&genre=article&issn=01007386&date=2000&volume=22&issue=1&spage=53 |
|
| dc.identifier.uri |
http://koha.mediu.edu.my:8181/jspui/handle/123456789/4549 |
|
| dc.description |
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. |
|
| dc.publisher |
The Brazilian Society of Mechanical Sciences |
|
| dc.source |
Journal of the Brazilian Society of Mechanical Sciences |
|
| dc.subject |
Coherent Vortices |
|
| dc.subject |
Mixing Layer |
|
| dc.subject |
Direct Numerical Simulation |
|
| dc.subject |
Large-Eddy Simulation |
|
| dc.subject |
Subgrid Scales Models |
|
| dc.title |
Dynamics of coherent vortices in mixing layers using direct numerical and large-eddy simulations |
|