Imaging 2D Turbulence

Article type: Research Article

Authors: Vorobieff, P. | Rivera, M. | Ecke, R.E.

Affiliations: Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA. | Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA. | Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Abstract: Gravity-driven flow in a soap film tunnel is spatially almost two-dimensional. A modification of particle-image velocimetry technique produces a comprehensive quantitative description of the flow. The technique allows simultaneous acquisition of the velocity (two components) in the plane of the film and the film thickness. The latter behaves as a scalar advected by the flow. The visualization method developed for these data sets uses the thickness field, the vorticity field and the instantaneous velocity streamline pattern for surface elevation, color and bump maps respectively, resulting in color surface images that reveal important features of the flow. In decaying turbulence behind a row of cylinders (2D grid turbulence), the images demonstrate the coarsening of the flow structure with downstream distance, which is the feature specific to turbulence in two dimensions. Strong correlation between thickness fluctuations and vorticity peaks also becomes apparent.

Keywords: soap films, 2D turbulence, PIV

Journal: Journal of Visualization, vol. 3, no. 4, pp. 323-330, 2001