论文标题
将上风集成方法应用于平行霍尔-MHD
Application of an Upwind Integration Method to Plane Parallel Hall-MHD
论文作者
论文摘要
我们研究了上风方案对中子星皮中霍尔和欧姆效应的数值收敛的影响。尽管对这些效果的模拟探索了各种几何形状和宽的物理参数范围,但它们仅限于霍尔参数的相对较低的值,扮演磁性雷诺数的作用,对于数值收敛的作用不应超过几百。 我们研究了平行的笛卡尔几何形状中磁场的演变。我们使用有限的差异方案来离散感应方程,然后通过Euler正向方法进行整合。将两种不同的方法用于集成在方程式中出现的对流术语:向前时间和空间中心(FTC)和朝向方案。我们在准确性和性能方面比较它们。我们根据平面与垂直场和霍尔参数的比率探索上风方法对收敛的影响。在低强度平面场的限制下,上风方案的使用提供了巨大的改进,从而导致模拟的收敛,其中Hall参数比FTC高2个数量级。如果平面场更强,上风仍然更好,但是,到达大厅参数的最大值的差异在10倍或几个以内。此外,我们注意到该方案是否分歧它们的行为有很大不同,而FTC会产生无限的能量,而上风方案仅暂时增加了总体磁场能。 总体而言,上风方案提高了模拟的效率,允许探索具有更高的电导率价值的环境,使我们比磁铁的现实环境条件更接近。
We study the impact of an Upwind scheme on the numerical convergence of simulations of the Hall and Ohmic effect in neutron stars crusts. While simulations of these effects have explored a variety of geometries and wide ranges of physical parameters, they are limited to relatively low values of the Hall parameter, playing the role of the magnetic Reynolds number, which should be not exceed a few hundred for numerical convergence. We study the evolution of the magnetic field in a plane-parallel Cartesian geometry. We discretise the induction equation using a finite difference scheme and then integrate it via the Euler forward method. Two different approaches are used for the integration of the advective terms appearing in the equation: a Forward Time and Central in Space (FTCS) and an Upwind scheme. We compare them in terms of accuracy and performance. We explore the impact of the Upwind method on convergence according to the ratio of planar to vertical field and the Hall parameter. In the limit of a low strength planar field the use of an Upwind scheme provides a vast improvement leading to the convergence of simulations where the Hall parameter is 2 orders of magnitude higher than that of the FTCS. Upwind is still better if the planar field is stronger, yet, the difference of the maximum value of the Hall parameter reached is within a factor of 10 or a few. Moreover, we notice if the schemes diverge their behaviour is very different, with FTCS producing infinite energy, while the Upwind scheme only temporarily increasing the overall magnetic field energy. Overall, the Upwind scheme enhances the efficiency of the simulations allowing the exploration of environments with higher value of electric conductivity getting us closer than before to realistic environmental conditions of magnetars.