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Energy and enstrophy transfer in decaying two-dimensional turbulence
M K Rivera1, W B Daniel, S Y Chen
1Condensed Matter & Thermal Physics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Physical Review Letters
|April 12, 2003
Summary
We experimentally studied two-dimensional turbulence, finding that the enstrophy cascade is weakly forward and the energy cascade is strongly upscale. This provides new insights into turbulence dynamics.
Area of Science:
- Fluid dynamics
- Turbulence research
Background:
- Two-dimensional turbulence exhibits complex energy and enstrophy transfer mechanisms.
- Understanding these cascades is crucial for modeling turbulent flows.
Purpose of the Study:
- To experimentally investigate the direct enstrophy cascade in decaying two-dimensional turbulence.
- To quantify enstrophy and energy fluxes using advanced velocimetry and filtering techniques.
Main Methods:
- Particle tracking velocimetry (PTV) was used to obtain velocity and vorticity fields.
- A filtering technique, inspired by large-eddy simulations, was applied to compute fluxes.
- Analysis focused on direct enstrophy transfer and inverse energy transfer.
Main Results:
- The direct enstrophy cascade was found to be weakly forward, with significant backscatter.
- The inverse energy cascade showed strong upscale transfer with moderate backscatter.
- Experimental data offered greater insight than traditional spectral or structure-function analyses.
Conclusions:
- The study provides direct experimental evidence of enstrophy and energy cascades in 2D turbulence.
- Findings highlight the interplay between forward enstrophy transfer and inverse energy transfer.
- The applied methods offer a valuable approach for studying turbulent phenomena.