论文标题
用于惯性限制融合胶囊的球形内爆模拟的Eulerian Vlasov-Fokker-Planck算法
An Eulerian Vlasov-Fokker-Planck Algorithm for Spherical Implosion Simulations of Inertial Confinement Fusion Capsules
论文作者
论文摘要
我们提出了一种数值算法,该算法可以实现惯性限制融合(ICF)胶囊内爆的相位空间自适应Eulerian Vlasov-Fokker-Planck(VFP)模拟。该方法依赖于将近期的质量,动量和能量保存的相位移动 - 移动网络适应性策略延长到球形几何形状。在配置空间中,我们采用网状运动偏微分方程(MMPDE)策略,而在速度空间中,网格被扩展/收缩/收缩,并随血浆的不断发展的温度和漂移速度而移动。通过将基本VFP方程转换为计算(逻辑)坐标,可以处理网格运动,并仔细离散以确保保护。为了处理球形爆炸系统中的空间和时间变化的动力学,我们在配置空间中为MMPDE制定了一种新型的非线性稳定策略。该策略依赖于非线性优化程序,该程序在网格质量和网格的体积变化之间进行了优化,以确保解决方案的准确性和稳定性。 ICF胶囊的内爆由几个边界条件驱动:1)弹性移动壁边界; 2)时间依赖于麦克斯韦尔·德里奇特(Maxwellian Dirichlet)边界; 3)压力驱动的拉格朗日边界。其中,压力驱动的拉格朗日边界驱动器是我们所知的新手。通过一组测试问题,包括Guderley和Van-Dyke内爆问题,这是使用Vlasov-Fokker-Planck模型报告的,我们的策略的实施得到了验证。
We present a numerical algorithm that enables a phase-space adaptive Eulerian Vlasov-Fokker-Planck (VFP) simulation of an inertial confinement fusion (ICF) capsule implosion. The approach relies on extending a recent mass, momentum, and energy conserving phase-space moving-mesh adaptivity strategy to spherical geometry. In configuration space, we employ a mesh motion partial differential equation (MMPDE) strategy while, in velocity space, the mesh is expanded/contracted and shifted with the plasma's evolving temperature and drift velocity. The mesh motion is dealt with by transforming the underlying VFP equations into a computational (logical) coordinate, with the resulting inertial terms carefully discretized to ensure conservation. To deal with the spatial and temporally varying dynamics in a spherically imploding system, we have developed a novel nonlinear stabilization strategy for MMPDE in the configuration space. The strategy relies on a nonlinear optimization procedure that optimizes between mesh quality and the volumetric rate change of the mesh to ensure both accuracy and stability of the solution. Implosions of ICF capsules are driven by several boundary conditions: 1) an elastic moving wall boundary; 2) a time-dependent Maxwellian Dirichlet boundary; and 3) a pressure-driven Lagrangian boundary. Of these, the pressure-driven Lagrangian boundary driver is new to our knowledge. The implementation of our strategy is verified through a set of test problems, including the Guderley and Van-Dyke implosion problems --the first-ever reported using a Vlasov-Fokker-Planck model.