c_NaCl 20[mM] "Initial and inlet salt concentration"
DNa 1.9e-9[m^2/s] "Diffusion coefficient, Na+"
DCl 2e-9[m^2/s] "Diffusion coefficient, Cl-"
z_Nap +1 "Charge, Na+"
z_Clm -1 "Charge, Cl-"