title: Large-scale intermittency in two-dimensional driven turbulence.
abstract: It is generally believed that two-dimensional turbulence is immune to intermittency possibly due to the absence of vortex stretching. However, in turbulence created in a freely suspended soap film by electromagnetic forcing, it is found that intermittency is not insignificant. We draw this conclusion based on the measured velocity structure function Sp(l) (identical to </deltavl/p>) proportional to l(zeta(p)) on scales l greater than the energy injection scale l(inj) . The scaling exponent zeta(p) vs p deviates from the expected linear relation and shows intermittent behavior comparable to that observed in fully developed three-dimensional turbulence in wind tunnels. Our measurements demonstrate that intermittency can be accounted for by the nonuniform distribution of saddle points in the flow.
authors.affiliation: Department of Physics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Yonggun
authors.initials: Y
authors.lastname: Jun
authors.forename: X L
authors.initials: XL
authors.lastname: Wu