Residence Time Distribution with Periodic Boundary Conditions
 

Hello ppl.
I have a question for all of you!
Is it possible to obtain a residence time distribution (RTD) of a tubular reactor using periodic boundary conditions (PBC)??!!
I'm determining the RTD with the tracer method, injecting a step of a non-diffusive tracer into the computational domain. The change of the tracer concentration, both in time and space, provides the RTD.
Now, I want to reduce the domain length (resulting to a substantial reduction of the required computational power and time) using PBC. But I do not know how to obtain the RTD using PBC!!
Thank you for your helping hand.