Intense focal and reynolds stress structures of a self-similar adverse pressure gradient turbulent boundary layer

Atsushi Sekimoto, Vassili Kitsios, Callum Atkinson, Javier Jimenez, Julio Soria

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearch

Abstract

The turbulence statistics and structures of a self-similar adverse pressure gradient turbulent boundary layer (APGTBL) are investigated using direct numerical simulation (DNS) of the flow at the verge of separation. The desired self-similar APG-TBL is achieved by a modification of the far-field velocity boundary condition. The required wallnormal velocity in the far-field to produce the necessary adverse pressure gradient was estimated based on the analytical free-stream streamwise velocity distribution for a flow at the point of separation, and the assumption that the streamlines of the outer flow follow the growth of the boundary layer thickness. The APG-TBL develops over a momentum thickness based Reynolds number upto 12000, and achieves a self-similar region of constant friction coefficient, pressure velocity and shape factor. Turbulence statistics in this region show self-similar collapse by using the scaling of the external velocity and the displacement thickness. In this study, the structure of the APG-TBL is investigated using topological methodology and visualisation techniques for a zero pressure gradient turbulent boundary layer (ZPG-TBL) and for the self-similar APG-TBL. The second invariants of the velocity gradient tensor (VGT), which are representative of coherent structures dominated by vortical motions, show a stark difference in the structure and location of coherent vortical structures that exists between the self-similar APGTBL and a ZPG-TBL. Further details based on the structure and distributions of the invariants of VGT and intense Reynolds stress structures of the self-similar APG-TBL are presented.

Original languageEnglish
Title of host publicationTenth International Symposium on Turbulence and Shear Flow Phenomena 2017
EditorsLex Smits
Place of PublicationChicago IL USA
PublisherInternational Symposium on Turbulence and Shear Flow Phenomena, TSFP10
Number of pages5
Volume1
Publication statusPublished - 2017
EventTurbulence and Shear Flow Phenomena 2017 - Swissotel, Chicago, United States of America
Duration: 6 Jul 20179 Jul 2017
Conference number: 10th
http://tsfp10.org/

Conference

ConferenceTurbulence and Shear Flow Phenomena 2017
Abbreviated titleTSFP-10
CountryUnited States of America
CityChicago
Period6/07/179/07/17
Internet address

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