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Surfing wave driven turbulence at a fluid surface
Nicolas FRANCOIS, Hua XIA, Horst PUNZMANN, Michael SHATS
Physics of Fluids Laboratory, The Australian National University
When a laminar flow becomes turbulent, its energy is spread over a range of scales in a process named energy cascade. It has recently been discovered that turbulent flows can be forced by steep Faraday waves at a fluid surface. Those flows possess features of two-dimensional turbulence [1,2,3]. In particular, an inverse energy cascade has been identified and a substantial amount of energy is stored into the turbulent fluctuations. An interesting question is whether it is possible to efficiently use the energy of this strongly out-of-equilibrium state.
In the wave driven turbulence, we show how to create floating devices able to extract energy from the turbulent motion fluctuations by coupling with underlying features of the energy cascade. The operational principle of these devices relies on the rectification of the chaotic motion of correlated bundles of fluid trajectories. By changing the shape of the device, we can turn it into a vehicle or a rotor powered by turbulence.
[1] A. V. Kameke, F. Huhn, G. Fernandez-Garcia, A. P. Munuzuri and V. Perez-Munuzuri, Phys. Rev. Lett. 107, 074502, (2011).
[2] N. Francois, H. Xia, H. Punzmann and M. Shats, Phys. Rev. Lett. 110, 194501, (2013).
[3] N. Francois, H. Xia, H. Punzmann, S. Ramsden and M. Shats, Phys. Rev. X 4, 021021, (2014).