[wuming]

Hi guys,
I can not figure out how to draw a grid with a boundary condition that was not required right at the exit of the bin. This way has been adopted in this article.(Srivastsva, A., & Sundaresan, S. (2003). Analysis of a frictional-kinetic model for gas-particle flow. Powder Technology, 129,72–85. )
The original text is as follows:（Simulations of particle discharge from a 2-D rectangular bin, 8 cm wide, 100 cm high and open at the top, were performed. The width of the central orifice at the bottom varied between 1.4 cm and 2 cm. A schematic of the simulation domain is shown in Fig. A 5-cm high region below the bin was included in the domain so that a boundary condition was not required right at the exit of the bin. The symmetry of the solution about the vertical centerline of the bin was assumed.）



Thank you in advance!