[R.B.Riddick]

Hi CFD Masters,

I am trying to model liquid Residence Time Distribution (RTD) in a fairly simple geometry (Baffled pipe). At the moment am trying to do this for a steady-state simulation and later on will do it for unsteady inlet boundary conditions. I have tried using the Lagrangian multiphase model (with a track file; recording residence time) but the results I obtained were unreliable when compared to the theoretical and experimental. I have embarked on solving this using a tracer dye. However I do not know how to do this in STAR-CCM+ and the help files were not very helpful. Some of the questions I have include;

1.How do I go about doing this in STAR CCM+; a step by step description would be helpful.
2.Do I have to set up a separate inlet for the tracer(dye)?
3. Does the tracer have to have the same properties as my Liquid (water)?
4. Will I need to specify a velocity for the Tracer
5. I would like for the dye to be injected as a pulse(within a very short period of time), how can I achieve this.
6. And finally how will I be able to obtain an RTD curve from post processing or from exporting simulation results?

Because the baffled tube is spatially periodic, I have a fully developed periodic boundary interface set up at the inlet and outlet. I do not if this will have any effect on the usual procedure followed to model RTD in STAR-CCM+.

Thank you for your help in advance.

R.B. Riddick