TY - GEN
T1 - Transitional and turbulent bent pipes
AU - Schlatter, Philipp
AU - Noorani, Azad
AU - Canton, Jacopo
AU - Hufnagel, Lorenz
AU - Örlü, Ramis
AU - Marin, Oana
AU - Merzari, Elia
N1 - Funding Information:
Financial support by the Swedish Research Council (VR) and the Knut and Alice Wallenberg Foundation (KAW) is gratefully acknowledged. Most of the simulations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at the National Supercomputer Centre (NSC) and PDC (Stockholm). Additional simulations were performed within the DECI-project PIPETURB.
Publisher Copyright:
© Springer International Publishing AG 2017.
PY - 2017
Y1 - 2017
N2 - We review a number of aspects of the transitional and turbulent flow in bent pipes, obtained at KTH using the spectral-element code Nek5000. This flow, sometimes also called Dean flow, is characterised by the appearance of Dean vortices, which arise due to the action of the centrifugal force in the bend. We start with reviewing recent stability analysis in the toroidal flow, and conclude that for all curvatures δ>0 an exponential instability is present at a bulk Reynolds number of about 4000. Further increasing the Reynolds number lets the flow go through a region with potential sub straight and sublaminar drag. An analysis using proper orthogonal decomposition (POD) reveals that wave-like motions are still present in the otherwise turbulent flow. Upon further increasing Re, the in-plane Dean vortices lead to a modulation of turbulence depending on the azimuthal position. The flow is then dominated by low-frequency so-called swirl-switching motion. This motion is studied in both a periodic and spatially developing framework. Finally, the effect of Dean vortices on Lagrangian inertial particles is studied.
AB - We review a number of aspects of the transitional and turbulent flow in bent pipes, obtained at KTH using the spectral-element code Nek5000. This flow, sometimes also called Dean flow, is characterised by the appearance of Dean vortices, which arise due to the action of the centrifugal force in the bend. We start with reviewing recent stability analysis in the toroidal flow, and conclude that for all curvatures δ>0 an exponential instability is present at a bulk Reynolds number of about 4000. Further increasing the Reynolds number lets the flow go through a region with potential sub straight and sublaminar drag. An analysis using proper orthogonal decomposition (POD) reveals that wave-like motions are still present in the otherwise turbulent flow. Upon further increasing Re, the in-plane Dean vortices lead to a modulation of turbulence depending on the azimuthal position. The flow is then dominated by low-frequency so-called swirl-switching motion. This motion is studied in both a periodic and spatially developing framework. Finally, the effect of Dean vortices on Lagrangian inertial particles is studied.
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U2 - 10.1007/978-3-319-57934-4_12
DO - 10.1007/978-3-319-57934-4_12
M3 - Conference contribution
AN - SCOPUS:85022344365
SN - 9783319579337
T3 - Springer Proceedings in Physics
SP - 81
EP - 87
BT - Progress in Turbulence VII - Proceedings of the iTi Conference in Turbulence 2016
A2 - Orlu, Ramis
A2 - Talamelli, Alessandro
A2 - Oberlack, Martin
A2 - Peinke, Joachim
PB - Springer Science and Business Media, LLC
T2 - 7th iTi Conference on Turbulence, 2016
Y2 - 7 September 2016 through 9 September 2016
ER -