Always learning wrote on calculating Residence time:

I am also trying a UDS/UDF as suggested on the fluent site. Here I set a UDS. Set its value at 0 at inlet.

Copy the UDF and use that for the rt_source calc. as below.

DEFINE_SOURCE(rt_source,c,t,dS,eqn) { real source = C_R(c,t); dS[eqn] = 0.0; return source; }

Yet with this I don't get any RTD?

Anyone has an idea what's the UDF/UDS he refered to? Is it in Fluent user Manual?

Thanks!

Try ...

http://clarify.fluent.com/eSupport/e...olution_id=619

Let me know how you get on, I am assuming you are wishing to do something similar.