PHAST HowToTransport Example "Solution type for SPECIFIED_BC not defined" Error

[asalas24]

Hello everyone,
I am working with the HowToTransport example file and encountered the following error when running my simulation:

ERROR: Solution type for SPECIFIED_BC not defined for cell 12078 (3,1,14) (276500,810500,-10).......ERROR: Stopping because of input errors.

I suspect this is because the Specified_BC boundary condition is missing an assigned solution, but I am unsure how to properly set it up within this example.

What I Have Done So Far:

Followed the HowToTransport.pdf instructions.
Enabled solute transport and transient flow.
Checked dispersivity parameters (default: 1 m).
Verified initial chemical conditions (CHEMISTRY_IC).
Ensured the steady-state head condition is set (flow.head.dat or ex5.head.200.dat).

What I Haven't Done (But Might Need To):

I haven't added any additional solutions beyond the default ones in the example file.
I don't know where to explicitly define the solution type for the boundary condition in transport.chem.dat.
I am unsure if I need to modify the BC Tree settings to properly link solutions to boundary conditions.

Questions:

In the HowToTransport example, where should I check or modify the solution type for Specified_BC?
Does transport.chem.dat already have the necessary solutions, or do I need to manually define them?
How do I ensure my BCs reference the correct solution number?
I appreciate any guidance, especially from anyone who has worked with this example before. Thanks!

[dlparkhurst]

For the specified head boundary using transport, you need to define the head for the boundary cells, the solution for the boundary cells, and whether the solution composition is "constant" or "associated".  Further, the head and solution may be defined as a time series.

It looks like you have not specified whether the solution is constant or associated. Constant means the concentrations do not change during the stress period; associated means the water that flows into the boundary cell has the specified concentrations.

In Phast4Windows, the specified head screen allows you to choose to define the head or the solution in the top left. The boxes to the right define the values to use for head or solution definitions with time, and the radio buttons at the bottom right select associated or constant.

If you export your .trans.dat file (File menu at top left of main screen) you should get something like this, where, in this case, the head starting from 0 seconds is 0 meters, and the solution at the boundary starting from 0 seconds is the solution defined by user number 1.

Code: [Select]

SPECIFIED_HEAD_BC
-box -0 0 0 1 1 0 GRID
-head
0 seconds 0
-associated_solution
0 seconds 1


[asalas24]

Hello,

Thank you for your previous help! I was able to fix the SPECIFIED_HEAD_BC issue as you suggested. However, now I'm running into a new error related to missing species in PHREEQC.

Here's the error message:

ERROR: Elements in species have not been tabulated, H+
ERROR: Elements in species have not been tabulated, H2O
ERROR: Elements in species have not been tabulated, NO3-
ERROR: Reaction for species has not been defined, H+

ERROR: PhreeqcRM failed.
ERROR: PhreeqcRM:: LoadDatabase

What I Have Done So Far:

* Verified the PHREEQC database path is correct (It is properly referencing phreeqc.dat).
* Checked that SOLUTION 1 is defined in transport.chem.dat (Includes pH, NO3-, H2O, etc.).
* Confirmed that CHEMISTRY_IC assigns solutions properly.
*SPECIFIED_HEAD_BC is correctly assigned and no longer has errors.

New Questions:

Why is PHREEQC not recognizing basic species like H+, H2O, and NO3- even though they are in the database?

Do I need to explicitly define SOLUTION_MASTER_SPECIES and SOLUTION_SPECIES in transport.chem.dat?

Should I check or modify anything in the PHREEQC database settings?

Could this be caused by the way my boundary conditions or reactions are set up?

I appreciate any guidance on this issue. Thanks again for your help!

[dlparkhurst]

I know you say otherwise, but it would make the most sense if you are loading transport.chem.dat as the database file. The first definitions in transport.chem.dat are SOLUTION_SPECIES that use NO3-, H+, and H2O, which would coincide with the error message.