Berlin 2014 – scientific programme

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P: Fachverband Plasmaphysik

P 22: Helmholtz Graduate School for Plasma Physics II

P 22.4: Topical Talk

Thursday, March 20, 2014, 12:05–12:30, SPA HS202

Nonuniversal power-law spectra in turbulent systems — •Vasil Bratanov¹, Frank Jenko¹, David Hatch², and Michael Wilczek³ — ¹Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, Boltzmannstraße 2, D-85748 Garching — ²Institute for Fusion Studies, University of Texas at Austin, Austin TX 78712, USA — ³Department of Mechanical Engineering, The Johns Hopkins University, 3400 NorthCharles Street, Baltimore MD 21218, USA

Turbulence is generally associated with universal power law spectra in scale ranges without significant drive or damping. Although many examples of turbulent systems do not exhibit such an inertial range, power law spectra may still be observed. In search for simple models exhibiting such a behavior, we first consider a modified version of the Kuramoto-Sivashinsky equation. By means of semi-analytical and numerical studies, one finds power laws with nonuniversal exponents at high wave numbers if the ratio of nonlinear and linear time scales is (roughly) scale-independent. As a further step we examine a two-dimensional fluid model with intrinsic drive and an additional cubic nonlinearity possessing a damping effect. Our analysis reveals again nonuniversal power laws that depend on the linear parameters.