The thin interface separating the inner turbulent region from the outer irrotational
fluid is analyzed in a direct numerical simulation of a spatially developing turbulent
mixing layer. A vorticity threshold is defined to detect the interface separating the
turbulent from the non-turbulent regions of the
flow, and to calculate statistics conditioned
on the distance from this interface. Velocity and passive scalar statistics are
computed and compared to the results of studies addressing other shear
as turbulent jets and wakes. The conditional statistics for velocity are in remarkable
agreement with the results for other types of free shear
flow available in the literature.
In addition, a detailed analysis of the passive scalar field (with Sc 1) in the vicinity
of the interface is presented. The scalar has a jump at the interface, even stronger
than that observed for velocity. The strong jump for the scalar has been observed
before in the case of high Schmidt number, but it is a new result for Schmidt number
of order one. Finally, the dissipation for the kinetic energy and the scalar are presented.
While the kinetic energy dissipation has its maximum far from the interface,
the scalar dissipation is characterized by a strong peak very close to the interface.
|Date of Award||Dec 2012|
- Physical Science and Engineering
|Supervisor||Fabrizio Bisetti (Supervisor)|
- Mixing Layer