论文标题
使用Delta-F方法和不断发展的背景Maxwellian的Delta-F方法驱动的湍流和区域流量的陀螺仪模拟
Gyrokinetic simulations of turbulence and zonal flows driven by steep profile gradients using a delta-f approach with an evolving background Maxwellian
论文作者
论文摘要
在系统远离其初始状态以及波动水平很高的情况下，长期的全球旋转湍流模拟尤其具有挑战性。在强大的梯度区域。对于粒子中的模拟，由于与Delta-F方案的控制变化较大的偏差，统计抽样噪声从大标记重量产生的积累使此类模拟通常不切实际。引入了具有时间依赖温度曲线的磁表面平均的自适应控制变化，以减轻前一种问题。在简化的无碰撞物理学下，这种自适应增量f方案被证明可减少纬向流中的噪声积累，而模拟的热通量在准稳态的湍流状态下。该方法还避免了在标准非自适应方案中发生的信噪比的崩溃，因此即使标记数较低，也可以达到数值收敛的结果。
Long global gyrokinetic turbulence simulations are particularly challenging in situations where the system deviates strongly from its initial state and when fluctuation level are high e.g. in strong gradient regions. For Particle-in-Cell simulations, statistical sampling noise accumulation from large marker weights due to large deviations from the control variate of a delta-f scheme make such simulations often impractical. An adaptive control variate in the form of a flux-surface-averaged Maxwellian with a time-dependent temperature profile is introduced in an attempt to alleviate the former problem. Under simplified collisionless physics, this adaptive delta-f scheme is shown to reduce noise accumulation in the zonal flows and the simulated heat flux in a quasi-steady turbulent state. The method also avoids the collapse of the signal-to-noise ratio which occurs in the standard non-adaptive scheme, and therefore, allows one to reach numerically converged results even with lower marker numbers.
