How to model diffusion
 

Hi,

I have a problem with modelisation of gaseous diffusion in CFX. In fact I would like to model the diffusion of CH4 in a vertical convergent pipe (it is like a cone without its top). At t=0, there is no ch4 in the volume. But the basis is at a constant concentration c0. And it should diffuse in the volume. I don t know how to input this in cfx (i m a beginner). I tried with a mass flow inlet, but that is not what I want.

Please, can someone help me?

Re: How to model diffusion
 

Hi Aboulard. can you please give more details of the problem. I don't understand in what phase methane is diffusing and whether it is mere molecular diffusion or convective diffusion also.

Sameer

Re: How to model diffusion
 

Hi Sameer

Sorry for lack of information.

It is molecular diffusion of gaseous methane in air. No convection.

Aboulard

Re: How to model diffusion
 

Dear Aboulard, From the details you have given, I would suggest you to use a single domain(with single phase i.e. air) with additional variable for CH4. In domain definition you give molecular diffusivity and use source point for CH4 at desired location in domain. I hope this will work.

Sameer