SOLUTION 1-81                    # mobile 1-40, immobile 42-81
 Na 1
EXCHANGE 1-81                    # Distribute exchanger homogeneously...
 X 1.1e-3;   -equilibrate 1
                                 # Distribute X heterogeneously, î_im = 0.1 î_m = 0.2
                                 # All X in mobile, X_m = X * (î_im + î_m)/î_m ...
#EXCHANGE 1-40
# X 1.65e-3; -equil 1
                                 # All X in immobile, X_im = X * (î_im + î_m)/î_im ...
#EXCHANGE 42-81
# X 3.3e-3;  -equil 1
END

SOLUTION 0; Ca 0.6; Cl 1.2; END
TRANSPORT
 -cells 40; -length 2e-3; -shifts 176
 -time_step 12.6                 # note smaller timestep: higher flow velocity
 -punch 40
                                 # 1 stagnant layer, à = 6.8e-4/s, î_m = 0.2, î_im = 0.1
 -stagnant 1 6.8e-4 0.2 0.1
 -disp   0.002
USER_GRAPH
 -head PV Na Cl Ca
 -axis_titles "Pore Volumes" "mmol/L"
 -plot t
 -start
                       # with stagnant zones, PV = last_cell_no * (î_m + î_im) / î_m ...
 10 graph_x (step_no + 0.5) / (cell_no * 1.5)
 20 graph_y tot("Na")*1e3, tot("Cl")*1e3, tot("Ca")*1e3
 -end
PRINT
 -reset  false
END