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Investigations of coherent structures in near-wall turbulence and large wall-shear stress events using Shake-The-Box

Schröder, Andreas and Schanz, Daniel and Geisler, Reinhard and Gesemann, Sebastian (2016) Investigations of coherent structures in near-wall turbulence and large wall-shear stress events using Shake-The-Box. 18th International Symposium on Applications of Laser Techniques to Fluid Mechanics, 04. - 07. July 2016, Lisbon, Portugal.

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Official URL: http://ltces.dem.ist.utl.pt/lxlaser/lxlaser2014/finalworks2014/papers/04.1_6_320paper.pdf

Abstract

A large portion of aerodynamic drag is produced by turbulent flow structures in the near-wall region which have significant influence on the amplitude and direction of wall-shear stress events acting on the surface. Furthermore, the impact of (very) large-scale structures present in the logarithmic region of a turbulent boundary layer onto the near-wall region has been high-lighted in recent years e.g. by Mathis et al. (2013) and Schlatter and Örlu (2011). Local back-flow close to the wall and thus negative wall-shear stress is a rare phenomenon in zero pressure gradient (ZPG)- turbulent boundary layers (TBL) and is caused by spanwise vorticity [Lenaers et al (2012)], but only limited experimental data are available (e.g. with micropillars [Bruecker 2015]) which cannot directly support investigations on the related role of coherent structures. Thus it is of great importance to enhance the understanding of the physics of near-wall turbulence, especially for the dynamics of extreme wall-shear stress events and related sweep-streak interactions, both from a fundamental and an engineering point of view. Due to strong wall-normal velocity gradients in the immediate wall region of a TBL a Tomo PIV [Elsinga et al. 2006][Scarano 2013] application would fail in delivering the desired quantities in 3D due to the low-pass filtering effect of correlation windows [Raffel et al 2007]. Therefore, the novel Lagrangian particle tracking method Shake-The-Box (STB) [Schanz et al. 2013a, Schanz et al. 2014] has been applied to a ZPG-TBL in order to gain time-resolved and volumetric velocity measurements including both components of the wall-shear stresses.

Item URL in elib:https://elib.dlr.de/101396/
Document Type:Conference or Workshop Item (Speech)
Additional Information:Paper 03.3_2_180
Title:Investigations of coherent structures in near-wall turbulence and large wall-shear stress events using Shake-The-Box
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schröder, Andreasandreas.schroeder (at) dlr.deUNSPECIFIED
Schanz, Danieldaniel.schanz (at) dlr.deUNSPECIFIED
Geisler, Reinhardreinhard.geisler (at) dlr.deUNSPECIFIED
Gesemann, Sebastiansebastian.gesemann (at) dlr.deUNSPECIFIED
Date:2016
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:pp. 1-14
Series Name:Conference Proceedings online, Book of Abstracts
Status:Published
Keywords:Shake-The-Box, turbulent boundary layer, coherent structure, wall-shear stress
Event Title:18th International Symposium on Applications of Laser Techniques to Fluid Mechanics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:04. - 07. July 2016
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Experimental Methods
Deposited By: Micknaus, Ilka
Deposited On:21 Jul 2016 16:38
Last Modified:26 Jul 2016 11:04

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