sliding User-Defined Memories along the mesh
 

Hi all,

I am modelling mass transfer in a domain. The system is composed of a porous medium, and a gas flowing through it.

I defined 10 UDM in my system. Each UDM represents a discretization point of the concentration profile.

To be clear: I have written an UDF that takes as an argument 10 points of a concentration profile, calculates a mass transfer, and gives out the new concentration profile. Each cell of the domain has then its own concentration profile (i.e. its own 10 UDM's).

Now, I would like to simulate of uniform downward motion of all the UDM's in the domain. If you imagine that the mesh is a (50x5 cells) rectangle for example, this means it contains 250 cells, and each cell has an associated concentration profile (i.e. 10UDMs per cell). At time step t=0+dt, I update all UDM's. Then at t = 0+2*dt, I would like to suppress all UDM's of the line 50 of my mesh, I would like to add a new line (line 1) of UDM's with given initial values, and finally I would like to shift all other 48 lines of UDM from one position down.

So now, I have 50x5 new concentration profiles, and then I do the same at the next time step, and so forth...

My question is: how to implement this into FLUENT? I guess I should take advantage of the EXECUTE_AT_END() macro, to do the algorithm at the end of each timestep. But how can I refer explicitly to the UDM's of the top line of the mesh, or to the UDM's of the bottom line of the mesh?

Thank you very much.

Ludovic.