Graphs in transport problems

[ravid]

Hello all,
I'm quite new to phreeqci. I'm trying to model a reactive transport problem in 1D column involving equilibrium and kinetic reactions.
I would like to plot two kinds of graphs for my simulation: concentration against time in a particular cell and a profile of the concentration along the length of the column at a given time. In the examples that I looked in there were either plots of temporal variation (when choosing only one cell to print) or of spatial variation (when manipulating the print_cells frequency to print only for one time). Can I generate both plots in a single run?
 I think I can generate one kind of graph with the print_cells option and the second kind by generating a select_output file by using the punch_cell option and plotting it later, but is there a better/simpler option?

Many thanks,
Ravid

[dlparkhurst]

You can subset by cell number or time step within the Basic programming for two USER_GRAPH data blocks. The following example plots concentration vs distance at shift 5, and concentrations for cell 3 vs time.

SOLUTION 1-10
   Na   1
   S(6)  0.5
END
SOLUTION 0
   Ca   1
   Cl    2
END
TRANSPORT
    -cells                 10
    -shifts                5
    -time_step             1 # seconds

USER_GRAPH 1
    -headings               Distance Na SO4 Ca Cl
    -axis_titles            "Distance" "Concentration, mmol/kgw" ""
    -chart_title            "Concentrations at shift 5"
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
 10 if (step_no <> 5) then goto 100
 20 graph_x dist
 30 graph_y tot("Na")*1000
 40 graph_y tot("S(6)")*1000
 50 graph_y tot("Ca")*1000
 60 graph_y tot("Cl")*1000
100 REM end
  -end
    -active                 true
USER_GRAPH 2
    -headings               Time Na SO4 Ca Cl
    -axis_titles            "Time" "Concentration, mmol/kgw" ""
    -chart_title            "Concentrations at cell number 3"
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  t
  -start
 10 if (cell_no <> 3) then goto 100
 20 graph_x total_time
 30 graph_y tot("Na")*1000
 40 graph_y tot("S(6)")*1000
 50 graph_y tot("Ca")*1000
 60 graph_y tot("Cl")*1000
100 REM end
  -end
    -active                 true
end

[ravid]

Thanks.
That's just what I looking for.
Ravid

[snjaykdubey]

Dear Sir,

I have following basic doubts as follow:

A) I don't understand.How to define the distance in X axis in order to plot the graph Concentration Vs Distance(Cell).In your explanation to one of the same question you have plotted concentration vs specific cell(e.g cell 5).What if i would like to view the concentration profile in all cell. Is it possible. ? I would like to understand the concentration profile in 1-D Advection model.

B) In my model i have different composition in different cell. For example i have 10 metre coloumn and it is divided in 5. Each cell is 2 meter then is it possible to mention different composition in different cell.  I want to define cell with different dimension is it possible. How can i do that.?

C) In Transport command, I come to know that Cell*Length=Total Distance. How can i define distance in advection.

regards,
Sanjay

[dlparkhurst]

A. For cell n and constant cell length l, the distance to the center of cell n is l/2 + (n - 1) * l or (n - 1/2)*l. ADVECTION does not have distance or time (unless KINETICS are simulated), just cell number and shift number. You can assign distance to the cells or time to the shifts, but they are not part of the calculuation method. If you want to use specific time and distance, use can also use TRANSPORT with 0 dispersivity and 0 diffusion coefficient.

If you use USER_GRAPH and plot concentration vs X, you will be able to plot concentrations in all cells at shifts defined by ADVECTION or TRANSPORT; punch_frequency.

B. You can define different solutions and reactants for each cell. SOLUTION 1-5 ...; SOLUTION 6-10 ...; will define different solutions for cells 1-5 and cells 6-10.

As for different dimensions, PHREEQC requires that the transit time for each cell be the same. If the velocity is constant in the column then the cell lengths must be constant.

C. Use TRANSPORT instead.

[snjaykdubey]

thanks sir,