Vorticity isotropy in high Karlovitz number premixed flames
- Creators
- Bobbitt, Brock
- Blanquart, Guillaume
Abstract
The isotropy of the smallest turbulent scales is investigated in premixed turbulent combustion by analyzing the vorticity vector in a series of high Karlovitz number premixed flame direct numerical simulations. It is found that increasing the Karlovitz number and the ratio of the integral length scale to the flame thickness both reduce the level of anisotropy. By analyzing the vorticity transport equation, it is determined that the vortex stretching term is primarily responsible for the development of any anisotropy. The local dynamics of the vortex stretching term and vorticity resemble that of homogeneous isotropic turbulence to a greater extent at higher Karlovitz numbers. This results in small scale isotropy at sufficiently high Karlovitz numbers and supports a fundamental similarity of the behavior of the smallest turbulent scales throughout the flame and in homogeneous isotropic turbulence. At lower Karlovitz numbers, the vortex stretching term and the vorticity alignment in the strain-rate tensor eigenframe are altered by the flame. The integral length scale has minimal impact on these local dynamics but promotes the effects of the flame to be equal in all directions. The resulting isotropy in vorticity does not reflect a fundamental similarity between the smallest turbulent scales in the flame and in homogeneous isotropic turbulence.
Additional Information
© 2016 AIP Publishing. Received 15 March 2016; accepted 15 August 2016; published online 4 October 2016. This research was supported by the Department of Defense [Air Force Office of Scientific Research] under Award No. FA9550-12-1-0144. Views and opinions of and endorsements by the author(s) do not reflect those of the US Air Force or the Department of Defense. The authors also gratefully acknowledge the support of the ARCS Los Angeles Chapter.Attached Files
Published - 1.4962305.pdf
Files
Name | Size | Download all |
---|---|---|
md5:68c6ec1d8a373e75db3173ab98140697
|
3.2 MB | Preview Download |
Additional details
- Eprint ID
- 71143
- Resolver ID
- CaltechAUTHORS:20161017-090914240
- FA9550-12-1-0144
- Air Force Office of Scientific Research (AFOSR)
- ARCS Los Angeles Chapter
- Created
-
2016-10-17Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field