One area of concern in longwall coal mines is the active gob directly behind the longwall face, where high concentrations of methane are likely to accumulate and active roof caving occurs. Using computational fluid dynamics (CFD) to simulate gas flows in and through the gob, most researchers have represented the entire gob as a porous medium governed by Darcy’s law. However, Darcy-type porous flow may not be applicable for the highly porous and unconsolidated fringes of the gob. In addition, porous medium models do not allow for representative combustion modeling to simulate in-gob ignition and flame propagation. This study presents a hybrid approach to modeling the gob using CFD: the outer part of the gob is modeled as discrete objects that simulate coarse rock rubble, while the gob center is modeled as a porous medium.

在长壁煤矿中，一个令人关注的领域是直接位于长壁工作面后面的采空区，在那里可能会积聚高浓度的甲烷，并且会发生主动顶放。大多数研究人员使用计算流体力学（CFD）来模拟通过和通过采空区的气体流动，将整个采空区表示为受达西定律控制的多孔介质。但是，达西型多孔流可能不适用于料滴的高度多孔和未固结的边缘。另外，多孔介质模型不允许进行有代表性的燃烧模型来模拟吸气点火和火焰传播。这项研究提出了一种使用CFD建模料滴的混合方法：料滴的外部被建模为离散对象，可模拟粗糙的岩石碎石，而料斗的中心则被建模为多孔介质。