Numerical studies of viscous flow around straight and curved tandem cylinders
Doctoral thesis
Permanent lenke
https://hdl.handle.net/11250/3122032Utgivelsesdato
2024Metadata
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- Institutt for marin teknikk [3584]
Sammendrag
The physics of flow around straight and curved cylinders in tandem is investigated by means of direct numerical simulations (DNS), for transitional and turbulent flow regimes.
For straight tandem cylinders in the reattachment regime, the effect on the gap and wake flow of transition to turbulence in the shear layers is scrutinized, along with the interaction between large-scale recirculating gap vortices and the development of the gap shear layers. The role of flow three-dimensionality in the gap and wake is studied. It is discovered that tandem cylinder flow regimes may be spanwise cellular and asymmetric in the gap region. The physical mechanism behind such cellular flow regime variations is discussed.
Tandem cylinders with axial curvature are studied for the first time. The convex configuration, where the incoming flow is directed towards the outside of the cylinder curvature, is chosen. The effect of axial flow on the forces on the cylinders and their characteristic frequencies is addressed, as well as spanwise variation of tandem cylinder flow regimes. Several flow regimes co-exist along the span, and some of these are unstable, which has a profound effect on the development of the wake. The flow topology of the gap and wake, vortex shedding modes and the complex interaction between the spanwise localized flow regimes are discussed in detail. The effect of transition to turbulence either in the wake or in the shear layers is addressed, as is the interaction between the primary instability and the shear layer instability, under influence of axial flow.
Består av
Paper 1: Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge Ingolf; Jiang, Fengjian. Revisiting the reattachment regime: a closer look at tandem cylinder flow at Re=10000. Journal of Fluid Mechanics 2022 ;Volum 953. s. 1-31 https://doi.org/10.1017/jfm.2022.960 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/),Paper 2: Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge; Jiang, Fengjian. Asymmetric cellular bi-stability in the gap between tandem cylinders. Journal of Fluid Mechanics 2023 ;Volum 966. https://doi.org/10.1017/jfm.2023.468 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0)
Paper 3: Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge Ingolf; Jiang, Fengjian. Flow Around Curved Tandem Cylinders. Journal of Fluids Engineering - Trancactions of The ASME 2022 ;Volum 144.(12) https://doi.org/10.1115/1.4054890
Paper 4: Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge; Jiang, Fengjian. Flow topology in the gap and wake of convex curved tandem cylinders. Journal of Fluid Mechanics 2023 ;Volum 976. https://doi.org/10.1017/jfm.2023.933 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0)
Paper 5: Aasland, T. E., Pettersen, B., Andersson, H. I. & Jiang, F. Turbulent flow around convex curved tandem cylinders.