EFFECT OF INTERACTING RAREFACTION WAVES ON RELATIVISTICALLY HOT JETS
EFFECT OF INTERACTING RAREFACTION WAVES ON RELATIVISTICALLY HOT JETS
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DOI：
10.1088/0004-637x/751/2/140
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
J. Matsumoto;Y. Masada;K. Shibata
中科院分区：
文献类型：
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作者：
J. Matsumoto;Y. Masada;K. Shibata
通过相对论流体动力学模拟研究了稀疏加速对相对论热射流的传播动力学和结构的影响。我们强调在圆柱形射流与周围介质之间的界面处激发的稀疏波的非线性相互作用。从具有径向射流结构的简化一维（1D）模型中，我们发现，由于射流中心区域中相互作用的稀疏波而导致相对论压力的减小，瞬时产生了比单一稀疏加速所预期的更强大的整体射流推力。这导致热能和体动能之间的循环原位能量转换，从而引起射流的径向振荡运动。振荡时间尺度以射流与环境介质的初始压力比为特征，并遵循简单的比例关系τoscillation∝(Pjet, 0/Pamb, 0)1/2。扩展的二维模拟证实，一维系统中的这种径向振荡运动表现为在更现实的情况下射流结构的调制，即相对论性热射流通过环境介质传播。我们发现，当环境介质具有幂律压力分布时，调制结构中沿射流传播方向的重约束区域大小λ按照自相似关系λ∝tα/2演化，其中α是压力分布的幂律指数。
The effect of rarefaction acceleration on the propagation dynamics and structure of relativistically hot jets is studied through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excited at the interface between a cylindrical jet and the surrounding medium. From simplified one-dimensional (1D) models with radial jet structure, we find that a decrease in the relativistic pressure due to the interacting rarefaction waves in the central zone of the jet transiently yields a more powerful boost of the bulk jet than that expected from single rarefaction acceleration. This leads to a cyclic in situ energy conversion between thermal and bulk kinetic energies, which induces radial oscillating motion of the jet. The oscillation timescale is characterized by the initial pressure ratio of the jet to the ambient medium and follows a simple scaling relation, τoscillation∝(Pjet, 0/Pamb, 0)1/2. Extended two-dimensional simulations confirm that this radial oscillating motion in the 1D system manifests as modulation of the structure of the jet in a more realistic situation where a relativistically hot jet propagates through an ambient medium. We find that when the ambient medium has a power-law pressure distribution, the size of the reconfinement region along the propagation direction of the jet in the modulation structure λ evolves according to a self-similar relation λ∝tα/2, where α is the power-law index of the pressure distribution.