Speed and structure of turbulent fronts in pipe flow Journal Article

Author(s): Song, Baofang; Barkley, Dwight; Hof, Björn; Avila, Marc
Article Title: Speed and structure of turbulent fronts in pipe flow
Affiliation IST Austria
Abstract: Using extensive direct numerical simulations, the dynamics of laminar-turbulent fronts in pipe flow is investigated for Reynolds numbers between and 5500. We here investigate the physical distinction between the fronts of weak and strong slugs both by analysing the turbulent kinetic energy budget and by comparing the downstream front motion to the advection speed of bulk turbulent structures. Our study shows that weak downstream fronts travel slower than turbulent structures in the bulk and correspond to decaying turbulence at the front. At the downstream front speed becomes faster than the advection speed, marking the onset of strong fronts. In contrast to weak fronts, turbulent eddies are generated at strong fronts by feeding on the downstream laminar flow. Our study also suggests that temporal fluctuations of production and dissipation at the downstream laminar-turbulent front drive the dynamical switches between the two types of front observed up to.
Keywords: Transition to turbulence; turbulent flows
Journal Title: Journal of Fluid Mechanics
Volume: 813
ISSN: 1469-7645
Publisher: Cambridge University Press  
Date Published: 2017-02-25
Start Page: 1045
End Page: 1059
DOI: 10.1017/jfm.2017.14
Notes: We thank Dr A. P. Willis for sharing his spectral toroidal-poloidal pipe flow code and A. Guseva for reading the manuscript. We acknowledge the Deutsche Forschungsgemeinschaft (Project no. FOR 1182), and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. B.S. acknowledges financial support from the Chinese State Scholarship Fund under grant no. 2010629145, support from the Max Planck Society and the Institute of Science and Technology Austria (IST Austria). We acknowledge the computing resources from Gesellschaft für wissenschaftliche Datenverarbeitung Göttingen (GWDG), the Jülich Supercomputing Centre (grant HGU16), the Regionalen Rechenzentrums Erlangen (RRZE) and computing facilities at IST Austria.
Open access: yes (repository)