TY - JOUR
T1 - Investigation of large scale motions in zero and adverse pressure gradient turbulent boundary layers using high-spatial-resolution particle image velocimetry
AU - Shehzad, Muhammad
AU - Sun, Bihai
AU - Jovic, Daniel
AU - Ostovan, Yasar
AU - Cuvier, Christophe
AU - Foucaut, Jean Marc
AU - Willert, Christian
AU - Atkinson, Callum
AU - Soria, Julio
N1 - Funding Information:
The authors would like to acknowledge the support of the Australian Government of this research through an Australian Research Council Discovery grant. Callum Atkinson was supported by an ARC Discovery Early Career Researcher Award (DECRA) fellowship . Muhammad Shehzad acknowledges the Punjab Educational Endowment Fund (PEEF) , Punjab, Pakistan for funding his PhD research. Bihai Sun and Daniel Jovic gratefully acknowledge the support through an Australian Government Research Training Program (RTP) Scholarship . The research was also benefited from computational resources provided by the Pawsey Supercomputing Centre and the NCI Facility both supported by the Australian Government with access provided via a NCMAS grant, as well as the partner share of the NCI facility provided by Monash University through an ARC LIEF grant and the Multi-modal Australian ScienceS Imaging and Visualisation Environment (MASSIVE).
Publisher Copyright:
© 2021
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/11/1
Y1 - 2021/11/1
N2 - High-spatial-resolution (HSR) two-component, two-dimensional particle-image-velocimetry (2C-2D PIV) measurements of a zero-pressure-gradient (ZPG) turbulent boundary layer (TBL) and an adverse-pressure-gradient (APG)-TBL were taken in the Laboratoire de Mécanique des Fluides de Lille (LMFL) High Reynolds number Boundary Layer Wind Tunnel. The ZPG-TBL has a momentum-thickness based Reynolds number Reδ2=δ2Ue∕ν=7,750 (where δ2 is the momentum thickness and Ue is the edge velocity), while the APG-TBL has a Reδ2=16,240 and a Clauser's pressure gradient parameter β=δ1Px∕τw=2.27 (where δ1 is the displacement thickness, Px is the pressure gradient in streamwise direction and τw is the wall shear stress). The 2C fluctuating flow field of each TBL was decomposed using proper orthogonal decomposition (POD) to investigate the large-scale motions (LSMs). The LSMs are found to be energized in the outer-layer, becoming stronger in the presence of the adverse-pressure-gradient. Profiles of the conditionally averaged Reynolds stresses show that high-momentum LSMs contribute more to the Reynolds stresses than low-momentum LSMs from the wall to the end of the log-layer while the opposite is found in the wake region. The cross-over point between the profiles of the conditionally averaged Reynolds stresses from the high- and low-momentum LSMs always has a higher value than the corresponding Reynolds stress from the unconditional ensemble average at the same wall-normal location. This difference is up to 80% in the Reynolds streamwise and shear stresses and up to 15% in the Reynolds wall-normal stresses. Furthermore, the cross-over point in the APG-TBL is found to be further from the wall than in the ZPG-TBL. The conditional Reynolds streamwise and shear stresses without the LSMs are reduced by up to 42% in the ZPG-TBL and by up to 50% in the APG-TBL, while having a minimal effect on the conditional Reynolds wall-normal stress without the LSMs in both the ZPG- and APG-TBL.
AB - High-spatial-resolution (HSR) two-component, two-dimensional particle-image-velocimetry (2C-2D PIV) measurements of a zero-pressure-gradient (ZPG) turbulent boundary layer (TBL) and an adverse-pressure-gradient (APG)-TBL were taken in the Laboratoire de Mécanique des Fluides de Lille (LMFL) High Reynolds number Boundary Layer Wind Tunnel. The ZPG-TBL has a momentum-thickness based Reynolds number Reδ2=δ2Ue∕ν=7,750 (where δ2 is the momentum thickness and Ue is the edge velocity), while the APG-TBL has a Reδ2=16,240 and a Clauser's pressure gradient parameter β=δ1Px∕τw=2.27 (where δ1 is the displacement thickness, Px is the pressure gradient in streamwise direction and τw is the wall shear stress). The 2C fluctuating flow field of each TBL was decomposed using proper orthogonal decomposition (POD) to investigate the large-scale motions (LSMs). The LSMs are found to be energized in the outer-layer, becoming stronger in the presence of the adverse-pressure-gradient. Profiles of the conditionally averaged Reynolds stresses show that high-momentum LSMs contribute more to the Reynolds stresses than low-momentum LSMs from the wall to the end of the log-layer while the opposite is found in the wake region. The cross-over point between the profiles of the conditionally averaged Reynolds stresses from the high- and low-momentum LSMs always has a higher value than the corresponding Reynolds stress from the unconditional ensemble average at the same wall-normal location. This difference is up to 80% in the Reynolds streamwise and shear stresses and up to 15% in the Reynolds wall-normal stresses. Furthermore, the cross-over point in the APG-TBL is found to be further from the wall than in the ZPG-TBL. The conditional Reynolds streamwise and shear stresses without the LSMs are reduced by up to 42% in the ZPG-TBL and by up to 50% in the APG-TBL, while having a minimal effect on the conditional Reynolds wall-normal stress without the LSMs in both the ZPG- and APG-TBL.
KW - Adverse pressure gradient
KW - High spatial resolution
KW - Large scale motions
KW - PIV
KW - Turbulent boundary layer
KW - Zero pressure gradient
UR - https://www.scopus.com/pages/publications/85109198889
U2 - 10.1016/j.expthermflusci.2021.110469
DO - 10.1016/j.expthermflusci.2021.110469
M3 - Article
AN - SCOPUS:85109198889
SN - 0894-1777
VL - 129
JO - Experimental Thermal and Fluid Science
JF - Experimental Thermal and Fluid Science
M1 - 110469
ER -