problems with residence time distribution
 

hi guys!

i'm pretty new in simulating with ansys, so i need your help. i tried to calculate the residence time distribution for an microfluid mixer, in a simple case a tube with 2 inlets and 1 outlet. in our workgroup we use ansys V13

so i tried to calculate the rtd like it is described in the help:
// Modeling Guide // 17. User Fortran // 17.8. User Junction Box Examples // 17.8.2. Junction Box Example 2: Integrated Residence Time Distribution

in our group there already exists a pre-master for the mixer with 2 inlets and 1 outlets, so all settings, they need are fixed. i wanted to integrate the rtd for our evaluation...

so my steps were:
-create an additional variable (RTD) of type volumetric, unit [s]
- declare the RTD of type "transport equation" in the domain and set diffusity to zero

in the next step, i'm not sure what i exactly have to do.

in my pre i have several boundaries, each for every inlet and outlet and i do not exactly, what kind of settings and values i should choose, especially in boundary details and sources.
i have read suggestions about to set a source value of 1[s/s] to the eqaution, so that the fluid gets 1s older per second and the inlet condition for RTD=0 but i cannot find, where i could do this.

i hope someone can help me, i would be appreciate if...

best regards