Re: Transport in PHREEQC

["David L Parkhurst" <dlpark@xxxxxxxx>]

> Is it possible to take the input solution (SOLUTION
0), run it for a certain number of shifts, then reduce the concentrations,
say, 33%, run the new SOLUTION  0 for an additional number of shifts,
reduce the concentrations again, and so forth?

Yes, simply run TRANSPORT  (or ADVECTION) for a stress period, redefine
SOLUTION 0, and run another stress period (should not redefine solutions,
equilibrium_phases, etc within the column).

> I would like the SELECTED_OUTPUT file to show the final concentrations in
the last cell
after a series of these solutions have been run.  I have seen a limited
number of smaller-scale examples of this problem.

Don't define SELECTED_OUTPUT until the final stress period or turn on/off
printing to the selected output file with PRINT; -selected_output T/F.


SOLUTION 0  #first inflow solution

SOLUTIONS 1-20

SURFACE 1-20

EXCHANGE 1-20

ADVECTION
             -cells 20
             -shifts (correponding to time for the first SOLUTION 0)

END (needed here or not?)  Yes, put an end here or else the next SOLUTION 0
will overwrite the first SOLUTION 0.

SOLUTION 0  #second inflow solution

# SOLUTIONS 1-20

# SURFACE 1-20             Do not redefine these. They would replace the
contents of the column that was present at the end of the first ADVECTION.
By leaving them out, The next advection starts off where the previous
ADVECTION ended.

# EXCHANGE 1-20

ADVECTION
             -cells 20
             -shifts (corresponding to time for the second SOLUTION 0)

SELECTED_OUTPUT  # right, only the last ADVECTION results will be printed.

USER_PUNCH

END


David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225


                                                                                                               
                      dlevy@xxxxxxxxxx                                                                         
                      om (Dave Levy)           To:      David Parkhurst <dlpark@xxxxxxxx>                      
                                               cc:                                                             
In-Reply-To: <3.0.1.32.20010914102908.006a0f04@xxxxxxxxxxxxxxxxxxx>
                      09/14/01 10:29           Subject: Transport in PHREEQC                                   
                      AM                                                                                       
                                                                                                               
                                                                                                               



Hi Dr. Parkhurst:

Over the past year or so you have been very helpful in answering questions
regarding some specific questions I have had using PHREEQC to model
geochemical reactions and transport. This model initially used a constant
source term (representing acid tailing water) moving as one-dimensional
advective flow through aquifer material containing native groundwater.  I
would now like to model the same situation, but by incorporating a
decreasing source term. Is it possible to take the input solution (SOLUTION
0), run it for a certain number of shifts, then reduce the concentrations,
say, 33%, run the new SOLUTION  0 for an additional number of shifts,
reduce the concentrations again, and so forth?  I would like the
SELECTED_OUTPUT file to show the final concentrations in the last cell
after a series of these solutions have been run.  I have seen a limited
number of smaller-scale examples of this problem.  I am thinking that the
basic set up for a 20 cell model with exchange and surface adsorption
reactions (just for two solutions here) is as shown below.  I was hoping
you could provide some guidance and possibly take a look at my input file
once I get it setup.  My main concern is getting the SELECTED_OUTPUT and
END statements in the right place so that I know the model is doing what I
want it to do.  Are the keywords in the following example in the right
order?

SOLUTION 0  #first inflow solution

SOLUTIONS 1-20

SURFACE 1-20

EXCHANGE 1-20

ADVECTION
             -cells 20
             -shifts (correponding to time for the first SOLUTION 0)

END (needed here or not?)

SOLUTION 0  #second inflow solution

SOLUTIONS 1-20

SURFACE 1-20

EXCHANGE 1-20

ADVECTION
             -cells 20
             -shifts (corresponding to time for the second SOLUTION 0)

SELECTED_OUTPUT

USER_PUNCH

END





-----------------------------------------------------
David B. Levy, Ph.D.
Soil Scientist/Geochemist
Shepherd Miller, Inc.
3801 Automation Way Suite 100
Fort Collins, CO 80525
Phone: 970.223.9600
FAX:   970.223.7171