BOUNDARY-LAYER DEVELOPMENT AFTER A SEPARATED REGION

Authors
Citation
Ip. Castro et E. Epik, BOUNDARY-LAYER DEVELOPMENT AFTER A SEPARATED REGION, Journal of Fluid Mechanics, 374, 1998, pp. 91-116
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Mechanics,"Phsycs, Fluid & Plasmas
Journal title
ISSN journal
0022-1120
Volume
374
Year of publication
1998
Pages
91 - 116
Database
ISI
SICI code
0022-1120(1998)374:<91:BDAASR>2.0.ZU;2-8
Abstract
Measurements obtained in boundary layers developing downstream of the highly turbulent, separated flow generated at the leading edge of a bl unt flat plate are presented. Two cases are considered: first, when th ere is only very low (wind tunnel) turbulence present in the free-stre am flow and, second, when roughly isotropic, homogeneous turbulence is introduced. With conditions adjusted to ensure that the separated reg ion was of the same length in both cases, the flow around reattachment was significantly different and subsequent differences in the develop ment rate of the two boundary layers are identified. The paper complem ents, but is much more extensive than, the earlier presentation of som e of the basic data (Castro & Epik 1996), confirming not only that the development process is very slow, but also that it is nonmonotonic. T urbulence stress levels fall below those typical of zero-pressure-grad ient boundary layers and, in many ways, the boundary layer has feature s similar to those found in standard boundary layers perturbed by free -stream turbulence. It is argued that, at least as far as the turbulen ce structure is concerned, the inner layer region develops no more qui ckly than does the outer flow and it is the latter which essentially d etermines the overall rate of development of the whole flow. Some nume rical computations are used to assess the extent to which current turb ulence models are adequate for such flows.