Flow topology of rare back flow events and critical points in turbulent channels and toroidal pipes

Chin C, Vinuesa R, Orlu R, Cardesa J, Noorani A, Schlatter P, Chong MS (2018)

Publication Type: Conference contribution

Publication year: 2018

Publisher: Institute of Physics Publishing

Book Volume: 1001

Conference Proceedings Title: Journal of Physics: Conference Series

Event location: Madrid, ESP

DOI: 10.1088/1742-6596/1001/1/012002

Abstract

A study of the back flow events and critical points in the flow through a toroidal pipe at friction Reynolds number Reτ ≈ 650 is performed and compared with the results in a turbulent channel flow at Reτ ≈ 934. The statistics and topological properties of the back flow events are analysed and discussed. Conditionally-averaged flow fields in the vicinity of the back flow event are obtained, and the results for the torus show a similar streamwise wall-shear stress topology which varies considerably for the spanwise wall-shear stress when compared to the channel flow. The comparison between the toroidal pipe and channel flows also shows fewer back flow events and critical points in the torus. This cannot be solely attributed to differences in Reynolds number, but is a clear effect of the secondary flow present in the toroidal pipe. A possible mechanism is the effect of the secondary flow present in the torus, which convects momentum from the inner to the outer bend through the core of the pipe, and back from the outer to the inner bend through the pipe walls. In the region around the critical points, the skin-friction streamlines and vorticity lines exhibit similar flow characteristics with a node and saddle pair for both flows. These results indicate that back flow events and critical points are genuine features of wall-bounded turbulence, and are not artifacts of specific boundary or inflow conditions in simulations and/or measurement uncertainties in experiments.

Authors with CRIS profile

Philipp Schlatter

Involved external institutions

University of Adelaide AU Australia (AU) Royal Institute of Technology / Kungliga Tekniska Högskolan (KTH) SE Sweden (SE) Universidad Politécnica de Madrid (UPM) ES Spain (ES) The University of Melbourne AU Australia (AU)

How to cite

APA:

Chin, C., Vinuesa, R., Orlu, R., Cardesa, J., Noorani, A., Schlatter, P., & Chong, M.S. (2018). Flow topology of rare back flow events and critical points in turbulent channels and toroidal pipes. In Javier Jimenez (Eds.), Journal of Physics: Conference Series. Madrid, ESP: Institute of Physics Publishing.

MLA:

Chin, C., et al. "Flow topology of rare back flow events and critical points in turbulent channels and toroidal pipes." Proceedings of the 3rd Madrid Summer School on Turbulence, Madrid, ESP Ed. Javier Jimenez, Institute of Physics Publishing, 2018.

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