I want to model a tracer step injection in a flow, using the unsteady solver. I would like to set the tracer concentration in one particular cell (the injection point) to a particular constant value at the beginning of each time step. Can someone tell me if this is a good idea and how to implement it in fluent.

Hi, I do so when I use a numerical tracer. To define the zone where to put the value of the concentration, you have to go in the "Adapt/Region" menu. Give the coordinates of the zone and "Mark" it, afterwards this zone will appear in the Solve/Initialize/Patch and your zone will appear in "Register to Patch", select it as well as the scalar you want to patch and set the value. Besides, you have to define the diffusion coefficient in "Materials" for your tracer in the fluid.

hi,Lohen: my model is about gas/water mix steady flowing in a big vessel. I use eulerian multiphase model. When I acquire the converged results, I want to add a tracer at the fluid inlet and use unsteady solver to calculate the tracer concentration at the outlet vs time step. But in fluent, I can not use multiphase and species models at the same time. Would you like give me some advice? Thank you very much! Thanks for any suggestion!