Goaf gas concentration distribution patterns at Panel 1412(1)were studied by means of computational fluid dynamics(CFD) numerical simulation.Considered two kinds of situations,one was simulated by buried pipe drainage in mined-out area,and the other was simulated without drainage.Goaf was regarded as porous medium,and simulation parameters we needed were based on field measured data and theoretical calculation.Compared and analyzed the two simulation results,we got a deep understanding of the similarities a...