Reply To: Species Transport Mixing Simulation – Setting Concentration of Tracer

[Rob]

Replot with node values off: the mesh looks very coarse in that region so you may not be patching into as much of a volume as you think. 

The patch is a mass into a volume. So, if you need a certain concentration you need to back calculate the mass into that volume to give the volume fraction. Note, in your experiment you add a known mass into the system, not a known concentration into a region of the tank.