Drag Modeling Effects on Simulations of Supersonic Jet-Induced Cratering in a Soil

The impact of the drag model in the simulation of turbulent granular flows is studied using databases here created through simulations of supersonic jet-induced cratering in granular soil. The simulations are based on a previously developed model, which was shown to be hyperbolic, thus permitting the unhindered propagation of pressure waves critical to craters produced by supersonic plumes. The goal is to identify predicted quantities from these simulations that show sufficient differences among simulations performed with different drag models; these quantities would warrant future experimental investigations determining which model is correct. Among all drag models examined, only two models are found applicable to the regime of investigation. Examination of the databases is conducted from the viewpoint of global quantities and detailed quantities. The results show that iso-contours and characteristic length scales are minimally affected by the employed drag law. In contrast, azimuthally averaged and root mean square ejecta-related quantities are more sensitive to the drag model employed, but only in the central part of the crater. This sensitivity is much larger for shallow craters having a parabolic cross section than for deep craters having a conical cross section, thus indicating the experimental configuration best suited to experimentally evaluate drag models

本研究针对湍流颗粒流模拟中的阻力模型影响展开探究，所用数据库源自颗粒土壤中超音速射流诱发冲坑的数值模拟结果。本次模拟基于已开发的双曲型模型，该模型可实现压力波的无阻碍传播，而压力波对于超音速羽流形成的冲坑而言至关重要。本研究的目标在于，从上述模拟结果中识别出在采用不同阻力模型的模拟间存在显著差异的预测量，此类量化指标将为后续实验验证最优阻力模型提供研究方向。在所考察的全部阻力模型中，仅两类模型适用于本研究的工况范围。本次数据库分析从全局量化指标与细节量化指标两个维度展开。研究结果表明，等值线与特征长度尺度受所用阻力定律的影响极小。与之相反，方位平均及与抛射物相关的均方根（root mean square）量化指标对所用阻力模型更为敏感，但该敏感性仅体现于冲坑的中心区域。相较于呈锥形截面的深冲坑，呈抛物截面的浅冲坑的此类敏感性更为显著，这一结果指明了最适合用于实验评估阻力模型的配置方案。