title: Energy and enstrophy transfer in decaying two-dimensional turbulence.
abstract: We present experimental data on the direct enstrophy cascade in decaying two-dimensional turbulence. Velocity and vorticity fields are obtained using particle tracking velocimetry. From those fields we directly compute the enstrophy and energy flux by using a filtering technique inspired by large-eddy simulations. This allows considerable insight into the physical processes of turbulence when compared with structure-function or spectral analysis. The direct cascade of enstrophy is weakly forward, with almost as much backscatter as down-scale enstrophy transfer, whereas the inverse energy cascade is strongly upscale with a modest amount of backscatter.
authors.affiliation: Condensed Matter & Thermal Physics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Rivera
authors.forename: W B
authors.initials: WB
authors.lastname: Daniel
authors.forename: S Y
authors.initials: SY
authors.lastname: Chen
authors.forename: R E
authors.initials: RE
authors.lastname: Ecke