Direct Evidence of a Dual Cascade in Gravitational Wave Turbulence.
Direct Evidence of a Dual Cascade in Gravitational Wave Turbulence.
复制标题
引力波湍流中双级联的直接证据。
DOI：
10.1103/physrevlett.127.131101
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发表时间：
2021
影响因子：
8.6
通讯作者：
S. Nazarenko
中科院分区：
文献类型：
--
作者：
S. Galtier;S. Nazarenko
本文首次对引力波湍流进行了直接数值模拟。广义相对论方程在周期盒中数值求解，其中对角度量张量g_{ij}<$g_{ii}（x，y，t）δ_{ij}只依赖于两个空间坐标，并附加了一个小尺度耗散项。我们只限于弱引力波和自由衰减的湍流。我们发现，在中间波数的初始度规激发导致能量和波作用的双重级联。当直接能量级联达到耗散尺度时，在能量从平台到幂律衰减的时间演化中观察到过渡，而逆级联前沿继续向低波数传播。的波数和频率波数谱被发现是兼容的弱波湍流的理论和特征的时间尺度的双级联是预期的四波共振相互作用。模拟结果表明，随着波动g_{11}和g_{22}的选择性放大，引力波作用的逆级联过程中，初始弱的引力波湍流有变强的趋势。
We present the first direct numerical simulation of gravitational wave turbulence. General relativity equations are solved numerically in a periodic box with a diagonal metric tensor depending on two space coordinates only, g_{ij}≡g_{ii}(x,y,t)δ_{ij}, and with an additional small-scale dissipative term. We limit ourselves to weak gravitational waves and to a freely decaying turbulence. We find that an initial metric excitation at intermediate wave number leads to a dual cascade of energy and wave action. When the direct energy cascade reaches the dissipative scales, a transition is observed in the temporal evolution of energy from a plateau to a power-law decay, while the inverse cascade front continues to propagate toward low wave numbers. The wave number and frequency-wave-number spectra are found to be compatible with the theory of weak wave turbulence and the characteristic timescale of the dual cascade is that expected for four-wave resonant interactions. The simulation reveals that an initially weak gravitational wave turbulence tends to become strong as the inverse cascade of wave action progresses with a selective amplification of the fluctuations g_{11} and g_{22}.