论文标题
从大规模到小规模发电机的过渡
Transition from large-scale to small-scale dynamo
论文作者
论文摘要
发电机方程用与罗伯茨流相对应的螺旋强迫求解。在完全湍流的状态下，流动的行为是罗伯茨在长时间尺度上的流动，以及在短时间尺度上的湍流波动。发电量受流量的长时间尺度控制，与以前的Karlsruhe实验结果一致。发电机机制受广义$α$效应的控制，其中包括通常的$α$效应和湍流扩散，以及所有高阶效应。除了开始之外，我们发现这种概括的$α$效应量表为$ o（rm^{ - 1}）$，暗示了小规模的发电机操作的收紧。即使大型场被人为地抑制，也会发生发电机的模拟证实。
The dynamo equations are solved numerically with a helical forcing corresponding to the Roberts flow. In the fully turbulent regime the flow behaves as a Roberts flow on long time scales, plus turbulent fluctuations at short time scales. The dynamo onset is controlled by the long time scales of the flow, in agreement with the former Karlsruhe experimental results. The dynamo mechanism is governed by a generalized $α$-effect which includes both usual $α$-effect and turbulent diffusion, plus all higher order effects. Beyond the onset we find that this generalized $α$-effect scales as $O(Rm^{-1})$ suggesting the take-over of small-scale dynamo action. This is confirmed by simulations in which dynamo occurs even if the large-scale field is artificially suppressed.
