多色孤子气体的 Riemann 问题:谱动力学理论的测试平台
Riemann problem for polychromatic soliton gases: a testbed for the spectral kinetic theory
AI总结:
本文以孤子气体 Riemann 问题为基准,构造多色孤子气体碰撞的谱动力学弱解,并通过与 KdV、fNLS 精确数值解的宏观量对比验证该理论。
摘要:
我们将孤子气体的 Riemann 问题用作基准,对 Korteweg-de Vries(KdV)方程和聚焦非线性 Schrödinger(fNLS)方程的谱动力学理论进行详细数值验证。我们构造了孤子气体动力学方程的弱解,用以描述两种稠密“多色”孤子气体的碰撞;这些气体由有限数量的“单色”组分组成,每个组分所含孤子在 Lax 对中散射算子的谱参数几乎相同。气体组分之间的相互作用在涌现的大尺度流体动力学演化中起关键作用。随后,我们利用谱动力学方程的解计算 KdV 和 fNLS 孤子气体中的宏观物理可观测量,并将其与从 KdV 和 fNLS 方程“精确”孤子气体数值解中提取的相应系综平均值进行比较。为在数值上合成稠密多色孤子气体,我们开发了一种新方法,该方法结合了所谓孤子凝聚体谱理论的最新进展,以及用于数值实现大 n 的 n-孤子解的高效算法。
英文摘要:
We use Riemann problem for soliton gas as a benchmark for a detailed numerical validation of the spectral kinetic theory for the Korteweg-de Vries (KdV) and the focusing nonlinear Schrödinger (fNLS) equations. We construct weak solutions to the kinetic equation for soliton gas describing collision of two dense "polychromatic" soliton gases composed of a finite number of "monochromatic" components, each consisting of solitons with nearly identical spectral parameters of the scattering operator in the Lax pair. The interaction between the gas components plays the key role in the emergent, large-scale hydrodynamic evolution. We then use the solutions of the spectral kinetic equation to evaluate macroscopic physical observables in KdV and fNLS soliton gases and compare them with the respective ensemble averages extracted from the "exact" soliton gas numerical solutions of the KdV and fNLS equations. To numerically synthesise dense polychromatic soliton gases we develop a new method which combines recent advances in the spectral theory of the so-called soliton condensates and the effective algorithms for the numerical realisation of $n$-soliton solutions with large $n$.
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