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arXiv 1607.02898physics.plasm-phnlin.AO
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漂移波-带状流中的相位相关对流扩散turbulence

Phase dependent advection-diffusion in drift wave - zonal flow turbulence

Sara Moradi, Johan Anderson

摘要:

在等离子体湍流理论中,由于系统的复杂性,许多非线性相互作用的波,相位的动力学往往被忽略,并使用所谓的随机相位近似(RPA)假设存在的Chirikov类标准的波随机性的开始。动态振幅被表示为复数$ψ= ψ_r + iψ_i = ae^{iθ}$,其中振幅缓慢变化,而相位快速变化,并且特别地,均匀地分布在间隔$[0;2π)$上。然而,人们可以期望相动力学可以在自组织和相干结构的形成中发挥作用。同样地,也可以预期RPA不足以考虑相位之间的相干相互作用。因此,在这项工作中,我们研究了相动力学的作用和不同模式之间的相耦合的特征时间演化的湍流。我们假设一个简单的湍流系统,所谓的随机振子模型可以采用。用随机振荡器解释湍流的想法。随机振子模型可以从Navier-Stokes方程或陀螺动力学方程中的非线性项的根本简化导出。在这种特殊情况下,我们采用了参考文献[1]中的具有被动平流和随机强迫的随机振子模型的基本方程。

英文摘要:

In plasma turbulence theory, due to the complexity of the system with many non-linearly interacting waves, the dynamics of the phases is often disregarded and the so-called random-phase approximation (RPA) is used assuming the existence of a Chirikov-like criterion for the onset of wave stochasticity. The dynamical amplitudes are represented as complex numbers, $ψ= ψ_r + iψ_i = ae^{iθ}$, with the amplitudes slowly varying whereas the phases are rapidly varying and, in particular, distributed uniformly over the interval $[0;2π)$. However, one could expect that the phase dynamics can play a role in the self-organisation and the formation of coherent structures. In the same manner it is also expected that the RPA falls short to take coherent interaction between phases into account. In this work therefore, we studied the role of phase dynamics and the coupling of phases between different modes on the characteristic time evolution of the turbulent. We assume a simple turbulent system where the so-called stochastic oscillator model can be employed. The idea of interpreting turbulence by stochastic oscillators. The stochastic oscillator models can be derived from radical simplifications of the nonlinear terms in the Navier-Stokes or Gyro-Kinetic equations. In this particular case we adopt the basic equation for the stochastic oscillator model with passive advection and random forcing from Ref.

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