Ct. Yap et Cw. Vanatta, EXPERIMENTAL STUDIES OF THE DEVELOPMENT OF QUASI-2-DIMENSIONAL TURBULENCE IN STABLY STRATIFIED FLUID, Dynamics of atmospheres and oceans, 19(1-4), 1993, pp. 289-323
Quasi-two-dimensional turbulence was generated by towing an array of v
ertical cylinders through a tank which was filled with a two-layer str
atified fluid. Sugar and Epsom salts were used, to give matching refra
ctive indices for the two layers. The interface between the two layers
was seeded with approximately 1000 neutrally buoyant particles. The e
volution of this quasi-two-dimensional turbulence was visualized by ph
otographing the fluorescent particles illuminated by a horizontal lase
r sheet traversing in the vertical direction. The three-dimensional pa
rticle velocity was obtained by digitizing the streaks. The evolution
of the velocity correlations, length scales, one-dimensional and two-d
imensional velocity and vorticity spectra were obtained for N=5.72 s(-
1), N=4.43 s(-1), and N=2.55 s(-1) (where N is the Brunt-Vaisala frequ
ency). The results showed the physical process of inverse energy casca
ding and the formation of dominant vortical structures under the influ
ence of density stratification. Compared with idealized two-dimensiona
l turbulence, the flow is highly dissipative at high N, as a result of
the frictional dissipation between the interface and the unstratified
layers.