Definition of geochemical boundary conditions (OGS6#PHREEQC)
I have trouble setting up the geochemical boundary condition by using OGS6#PHREEQC and hope someone can give me a hint.
With my understanding, each component must have its own boundary condition with OGS6 (If I am wrong, please correct me). What if only pure contamination (e.g., CO2(g) or CO2(aq)) is injected into the solution? Do other components (in the domain) also need their own boundary condition with a constant value, temporal-dependent, and others?? Then, I guess the calculation at the boundary is not correct due to the fixed boundary condition.
Steps to Reproduce the Problem
For example, initial gypsum (CaSO₄·2H₂O) concentration is 10 mole (domain), and C(4) is injected at the top boundary. Gypsum dissolves, and the concentration of Ca and S(6) increases.
Expected behavior: [What you expected to happen] Below is the simulation result using OGS5#IPhreeqc. The geochemical boundary condition is only applied to the contamination, C(4). The concentration of Ca and S(6) is high at the boundary (here, z=0) due to the gypsum dissolution (Figure 8).
Actual behavior: [What actually happened] Here (OGS6) is the simulation result when all (im)mobile species have their own boundary condition. Due to the fixed boundary condition, the change of Ca and S(6) concentration at the boundary can not be observed (concentration at the z=0 is fixed over simulation time )
How do I set up the appropriate geochemical boundary condition with OGS6#PHREEQC?
- Version: OpenGeoSys-6 version 6.3.1.
Thank you in advance :) Eunseon