Using the "Transport of Diluted Species" interface, a Poiseuille velocity field was imposed in the channel, with the magnitude determined by a parameterized pressure/viscosity term that was variable in time. In the first 20 seconds of the simulation, the velocity corresponded to an inlet pressure of 75 mbar, and two solute species were introduced by concentration constraint at the inlet, resulting in the introduction of a sample "plug". After 20 seconds, the concentration constraint at the inlet was set to zero and the pressure parameter increased to a value corresponding to the desired experimental velocity.