# diffusion of NaCl in clay membrane. Membrane opens up when DDL thickness reduces. KNOBS -numerical_derivatives true # This option speeds up the calculations in version 3.4.6 or later, comment it out in earlier versions -step_size 10; -pe_step_size 5; -iterations 1000 SOLUTION 0; Na 500; Cl 500 # saline outer solution END SOLUTION 1-20; Na 1; Cl 1; water 0.02 SOLUTION 21; Na 1; Cl 1 SURFACE_MASTER_SPECIES; Su Su- SURFACE_SPECIES; Su- = Su-; log_k 0 SURFACE 1-20; Su 0.1 1.786e5 1; -equil 1 -donnan debye_length 1 limit_DDL 0.98 viscosity 1 END PRINT -reset false TRANSPORT; -cells 15; -length 1e-2; -shifts 1 0; -bcon 1 3; -time 2.592e5 -multi_d true 1e-9 1 0 1 -implicit true # Another speed-up in version 3.5.1 or later, comment out in earlier versions USER_GRAPH -plot_concentration_vs x -axis_titles "Distance / m" "mol/L" "H2O_DDL / H2O_tot" -chart_title "Clay Membrane Diffusion" -axis_scale x_axis 0 0.1501 0.05 -axis_scale y_axis 0 0.601 0.2 -axis_scale sy_axis 0 1 -initial_solutions true -head dist Na Cl aq_DDL -start 10 if step_no > 0 then goto 60 20 if cell_no > 1 then goto 80 # concentrations at the boundary (x = 0, solution 0)... 30 graph_x 0 40 graph_y 0.5, 0.5 50 goto 80 60 graph_x dist # concentrations in the profile... 70 graph_y sys("Na"), sys("Cl") 72 graph_sy edl("water") 80 end -end END