1 dimension mass (gas) diffusion
 

Hello everyone,
I'm going to simulate the flow of an inert gas, I, between two perforated surface. This problem is treated as 1D. At the west surface there's a species named A having a concentration 10 moles/m3. At the east surface, 100 moles/m3. My objective is to predict the concentration profile of A between the two surfaces. the Inert velocity, diffusivity constant, distance and density values are set. my question are: (maybe a silly question but I'm 100% newbie)

1. what are the boundary types (gambit) for those two perforated surface? WALL or MASS_FLOW_INLET (or maybe others)?

2. where to define the diffusivity constant?

3. since the problem is treated as 1D while both gambit and fluent would only accept 2d and 3d, is it okay to set (in gambit) the interval count (meshing) to 1 for those two perforated surface?