SPHYNX：一种用于天体物理学应用的精确密度基SPH方法
SPHYNX: an accurate density-based SPH method for astrophysical applications
摘要：
流体动力学不稳定性和激波在天体物理情景中是普遍存在的。因此，对这些现象进行精确的数值模拟是正确建模和理解许多天体物理事件（如超新星，恒星碰撞或行星形成）的必要条件。在这项工作中，我们试图解决许多问题，光滑粒子流体动力学（SPH）技术在处理亚音速流体动力学不稳定性或冲击。为此，我们建立了一个新的SPH代码SPHYNX，其中包括SPH技术的许多最新进展和其他一些新的，我们在这里介绍。SPHYNX是牛顿型的，并且基于SPH技术的欧拉-拉格朗日公式。其显著特点是：使用积分方法来估计梯度;使用称为sinc核的灵活的插值器族，其抑制配对不稳定性;以及并入提供更好的单位分割的新型体积元素。与其他考虑与压力相关的体积元的现代公式不同，我们的体积元选择依赖于密度。SPHYNX保持质量，线性和角动量，能量，熵，并保持核归一化，即使在强烈的冲击。计算梯度的积分方法和新的体积元族之间的耦合减少了所谓的拉伸不稳定性。这两个功能有助于抑制阻尼，这往往会阻止增长的流体动力学不稳定性，在定期SPH代码。总体而言，SPHYNX已通过下述验证测试。对于相同的粒子设置和初始条件的结果是类似的（或更好的，在某些特定情况下）比与其他SPH计划，如GADGET-2，PSPH或与最近的密度无关的制定（DISPH）和保守再生核（CRKSPH）技术。
英文摘要：
Hydrodynamical instabilities and shocks are ubiquitous in astrophysical scenarios. Therefore, an accurate numerical simulation of these phenomena is mandatory to correctly model and understand many astrophysical events, such as Supernovas, stellar collisions, or planetary formation. In this work, we attempt to address many of the problems that the smoothed particle hydrodynamics (SPH) technique has when dealing with subsonic hydrodynamical instabilities or shocks. To that aim we built a new SPH code named SPHYNX, that includes many of the recent advances in the SPH technique and some other new ones, which we present here. SPHYNX is of Newtonian type and grounded in the Euler-Lagrange formulation of the SPH technique. Its distinctive features are: the use of an integral approach to estimating the gradients; the use of a flexible family of interpolators called sinc kernels, which suppress pairing instability; and the incorporation of a new type of volume element which provides a better partition of the unity. Unlike other modern formulations, which consider volume elements linked to pressure, our volume element choice relies on density. SPHYNX conserves mass, linear and angular momentum, energy, entropy, and preserves kernel normalization even in strong shocks. The coupling between the integral approach to calculate gradients and the new family of volume elements reduces the so-called tensile instability. Both features help to suppress the damp which often prevents the growth of hydrodynamic instabilities in regular SPH codes. On the whole, SPHYNX has passed the verification tests described below. For identical particle setting and initial conditions the results were similar (or better in some particular cases) than those obtained with other SPH schemes such as GADGET-2, PSPH or with the recent density-independent formulation (DISPH) and conservative reproducing kernel (CRKSPH) techniques.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
