论文标题
从Dem-Rans数值模拟中的行星沉积物传输的缩放定律
Scaling laws for planetary sediment transport from DEM-RANS numerical simulations
论文作者
论文摘要
我们使用既定的离散元素方法（DEM）雷诺平均纳维尔 - 斯托克斯（RANS）基于数值模型来模拟跨粒子 - 流体密度比率$ s $中的近七个数量级的无悬浮沉积物的运输，从属于subielian的运输（$ s）的范围（$ s = 2.65 $），均以高度的运输（$ s = 2.65 $） （$ s = 10^7 $），而以前的基于DEM的沉积物运输研究并不超过陆地风格的状况（$ s \ of2000 $）。在这些模拟和实验的指导下，我们在半验证方面得出了简单的缩放定律，以限制限制阈值和平衡风化的风速，都表现出相当不寻常的$ s^{1/3} $ - 依赖性。它们构成了一种简单的方法，可以在各种行星条件下对风化过程进行预测。该派生由基于第一原则的证据组成，即在相对温和的假设下，停止阈值物理仅由一个无尺度控制参数控制，而不是从维度分析中预期的两个。至关重要的是，与现有模型不同，此证明不会诉诸于床表面上方风湿层的颗粒相。从现有模型的池中，只有Pähtz等人的模型。 （\ textit {它捕获了戒烟阈值的缩放和$ s^{1/3} $ - 运输速率的依赖性，但无法捕获后者的叠加粒度依赖性。这暗示了对运输速率物理学的了解，并呼吁对此问题进行未来的研究。
We use an established discrete element method (DEM) Reynolds-averaged Navier--Stokes (RANS)-based numerical model to simulate non-suspended sediment transport across conditions encompassing almost seven orders of magnitude in the particle--fluid density ratio $s$, ranging from subaqueous transport ($s=2.65$) to aeolian transport in the highly rarefied atmosphere of Pluto ($s=10^7$), whereas previous DEM-based sediment transport studies did not exceed terrestrial aeolian conditions ($s\approx2000$). Guided by these simulations and by experiments, we semi-empirically derive simple scaling laws for the cessation threshold and rate of equilibrium aeolian transport, both exhibiting a rather unusual $s^{1/3}$-dependence. They constitute a simple means to make predictions of aeolian processes across a large range of planetary conditions. The derivation consists of a first-principle-based proof of the statement that, under relatively mild assumptions, the cessation threshold physics is controlled by only one dimensionless control parameter, rather than two expected from dimensional analysis. Crucially, unlike existing models, this proof does not resort to coarse-graining the particle phase of the aeolian transport layer above the bed surface. From the pool of existing models, only that by Pähtz et al. (\textit{J. Geophys. Res. Earth. Surf.}~126, e2020JF005859, 2021) is somewhat consistent with the combined numerical and experimental data. It captures the scaling of the cessation threshold and the $s^{1/3}$-dependence of the transport rate, but fails to capture the latter's superimposed grain size dependence. This hints at a lack of understanding of the transport rate physics and calls for future studies on this issue.
