After reviewing the variational approach to splitting mean flow and fluctuation kinetics in the standard Vlasov theory, the same method is applied to the drift-kinetic equation from Littlejohn's theory of guiding-center motion. This process sheds a new light on drift-ordered fluid (drift-fluid) models, whose anisotropic pressure tensor is then considered in detail. In addition, current drift-fluid models are completed by the insertion of magnetization terms ensuring momentum conservation. Magnetization currents are also shown to lead to challenging aspects when drift-fluid models are coupled to Maxwell's equations for the evolution of the electromagnetic field. In order to overcome these difficulties, a simplified guiding-center theory is proposed along with its possible applications to hybrid kinetic-fluid models.

中文翻译：

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变分平均波动分裂和漂移流体模型

在回顾了标准 Vlasov 理论中分裂平均流动和波动动力学的变分方法之后，将相同的方法应用于 Littlejohn 引导中心运动理论中的漂移动力学方程。这个过程为漂移有序流体（漂移流体）模型提供了新的思路，然后详细考虑了其各向异性压力张量。此外，电流漂移流体模型通过插入确保动量守恒的磁化项来完成。当漂移流体模型与电磁场演化的麦克斯韦方程耦合时，磁化电流也被证明会导致具有挑战性的方面。为了克服这些困难，提出了一种简化的引导中心理论及其对混合动力流体模型的可能应用。