Following the recent observation that turbulent pipe flow can be relaminarised bya relatively simple modification of the mean velocity profile, we here carry out aquantitative experimental investigation of this phenomenon. Our study confirms thata flat velocity profile leads to a collapse of turbulence and in order to achieve theblunted profile shape, we employ a moving pipe segment that is briefly and rapidlyshifted in the streamwise direction. The relaminarisation threshold and the minimumshift length and speeds are determined as a function of Reynolds number. Althoughturbulence is still active after the acceleration phase, the modulated profile possessesa severely decreased lift-up potential as measured by transient growth. As shown,this results in an exponential decay of fluctuations and the flow relaminarises. Whilethis method can be easily applied at low to moderate flow speeds, the minimumstreamwise length over which the acceleration needs to act increases linearly with theReynolds number.
Journal of Fluid Mechanics
Scarselli D, Kühnen J, Hof B. Relaminarising pipe flow by wall movement. Journal of Fluid Mechanics. 2019;867:934-948. doi:10.1017/jfm.2019.191
Scarselli, D., Kühnen, J., & Hof, B. (2019). Relaminarising pipe flow by wall movement. Journal of Fluid Mechanics. Cambridge University Press. https://doi.org/10.1017/jfm.2019.191
Scarselli, Davide, Jakob Kühnen, and Björn Hof. “Relaminarising Pipe Flow by Wall Movement.” Journal of Fluid Mechanics. Cambridge University Press, 2019. https://doi.org/10.1017/jfm.2019.191.
D. Scarselli, J. Kühnen, and B. Hof, “Relaminarising pipe flow by wall movement,” Journal of Fluid Mechanics, vol. 867. Cambridge University Press, pp. 934–948, 2019.
Scarselli D, Kühnen J, Hof B. 2019. Relaminarising pipe flow by wall movement. Journal of Fluid Mechanics. 867, 934–948.
Scarselli, Davide, et al. “Relaminarising Pipe Flow by Wall Movement.” Journal of Fluid Mechanics, vol. 867, Cambridge University Press, 2019, pp. 934–48, doi:10.1017/jfm.2019.191.
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