Kolmogorovian turbulence in transitional pipe flows
Rory T. Cerbus, Chien-chia Liu, Gustavo Gioia, Pinaki Chakraborty
KKolmogorovian turbulence in transitional pipe flows
Rory T. Cerbus, Chien-chia Liu, Gustavo Gioia, and Pinaki Chakraborty
Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, Japan 904-0495 (Dated: November 8, 2018)As everyone knows who has opened a kitchen faucet, pipe flow is laminar at low flow velocitiesand turbulent at high flow velocities. At intermediate velocities there is a transition wherein plugs oflaminar flow alternate along the pipe with “flashes” of a type of fluctuating, non-laminar flow whichremains poorly known. We show experimentally that the fluid friction of flash flow is diagnosticof turbulence. We also show that the statistics of flash flow are in keeping with Kolmogorov’sphenomenological theory of turbulence (so that, e.g., the energy spectra of both flash flow andturbulent flow satisfy small-scale universality). We conclude that transitional pipe flows are two-phase flows in which one phase is laminar and the other, carried by flashes, is turbulent in the senseof Kolmogorov.