Hi all,
As a rookie in using PetraSim, recently I'm struggling on choosing the right BCs for my simulations. Want to hear opinions from you guys.
Default BC in TOUGH2: no mass/energy flow. This case represents a model of a reservoir, which is analog to a "can", as all the boundaries are impermeable.
Fixed State BC: constant state at boundary. This case represents a modeled domain in an (approximately) infinitely large reservoir, e.g., a huge aquifer, as at the boundary cells all parameter remains identical to the IC, or "unaffected" by anything occurs in the modeled domain. Of course any desired parameter values can also be designated to the boundary cells, such as time-dependent BC.
Boundary cells with huge volume factor BC: same as the "Fixed State BC", as the boundary cells are large enough to damp out any change due to injections/productions in the inner domain.
Does my above statement make sense to you guys? For my particular case I want to model an area of interest in a infinitely large aquifer. To be physically consistent with the real situation, I set the "Fixed State" BC and the result looks quite creditable to me. But I'm need 120% confidence on that.
Moreover, somebody at work suggested a "Updated Fixed State BC", in which the primary variables at the boundary cells are set as fixed state but will be updated to be identical to the adjacent inner cells for every some time-steps. Do you guys think such BC is more realistic than the Fixed State BC (in which all parameters remain identical to the IC)? UPDATED: it turned out that the "Updated Fixed State BC" is identical to the original "Fixed State BC".
Thank you so much for being patient to read through this long post. Any comments and suggestions will be highly appreciated.
-JohnCO2