1. Advanced Contaminant-Transport Techniques

2. Review Version 9 CT Enhancements
Species element:
Can accept either decay rates or half-lives
Can be exported to, or imported from, Excel
Source element:
Acts as a Container
“Associated Cells” are now automatic
New Advective Transfer options:

3. Discuss User Issues
How can I apply a boundary condition to a pathway element?
How can I use the Source element to represent a complex engineered barrier system?

4. Pipe or Cell?
Generally, use Pipe elements only for steady-state flow systems!

5. Pipe Pathway Strengths & Limitations
Exact solution to very complex physical system
Limitations
Cannot apply solubility limits within pathway.
Species are discharged from a pathway based on the properties of the pathway at the time the species (or their parents) entered it.
“Looping” reaction chains are not permitted
e.g., A  B and B  A

6. Cell Pathway Strengths & Limitations
Flexibility
Stability & accuracy
Limitations
Tedious to construct networks
Numerical dispersion
α ~ L/2N

7. What are Partition Coefficients?
Defined as the ratio of the species’ concentration in medium X to its concentration in the reference fluid.
Useful concepts:
A sorbing solid with mass M is equivalent to a volume of water = M Kd
The retardation factor for a system, even a complex system:
Total Equivalent Volume / Flowing Volume

8. Fluids, Reference Fluids, Cloned Fluids
Fluids normally have specified partition factors. This gives them an implied solubility limit.
If you choose to specify solubilities for a fluid, you get implied partition factors.
If you clone a reference fluid, the partition factors = 1 and the solubilities can be different (if you use a link).