Flux boundary conditon

[Pak]

Dear all,

I wonder about how is implemented the flux boundary condition in Phreeqc. If I have C(xi, t) = C0 + (D/v)* (dC/dx)
where xi is the ghost cell at the beggining or at the end. I wonder how C0 is known, if I have for instance the following input:


Solution 0
...

Solution 1-20
...

Transport 1-20
...
- boundary_conditions  flux flux
...

I assume that c0 at the first cell would be the value in Solution 0, but what is the value for c0 at the end of the domain, is it the value in solution 20? or it is 0; If it is the value in solution 20, does it mean that it will change during the simulation?


Thanks

[dlparkhurst]

To be honest, I am not completely sure how the flux boundary is implemented. I am pretty sure that, assuming forward flow in TRANSPORT, solution 21 will be defined by advection from the column (and perhaps equal to solution 20 for the first step before advection). It will then be used for the flux boundary calculation.

I know that solution 20 will vary during the simulation.