### Session MA: Turbulence Theory III

8:00 AM–10:10 AM, Tuesday, November 25, 2008
Room: 001A

Chair: Bhimsen K. Shivamoggi, University of Central Florida

Abstract ID: BAPS.2008.DFD.MA.2

### Abstract: MA.00002 : Energy injection into two-dimensional turbulence: a scaling regime controlled by drag

8:13 AM–8:26 AM

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#### Authors:

Yue-Kin Tsang
(Scripps Institution of Oceanography, University of California, San Diego)

William Young
(Scripps Institution of Oceanography, University of California, San Diego)

The energy injection rate $\varepsilon$ is the most important single statistical quantity characterizing two-dimensional turbulence, and it plays a central role in Kraichnan's theory of inverse energy cascade. In most experiments and meteorological applications, $\varepsilon$ is not known a priori, as the fluid is driven by a body force rather than by prescribing $\varepsilon$. It is therefore important to understand the dependence of $\varepsilon$ on the external control parameters of a system. Drag is an important physical effect in many quasi-two-dimensional systems. Hence, we consider two-dimensional turbulence driven by steady sinusoidal body force at small scale, with linear drag of damping time scale $\mu^{-1}$ as the main dissipative mechanism. We present numerical results that reveal a new scaling regime in which $\varepsilon \sim \mu^{1/3}$. A theoretical model in which the directly forced mode is randomly swept by the large scale motion across the stationary sinusoidal forcing pattern is used to explain the observations.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.DFD.MA.2