Hi Guys,

I am trying to calc the residence time in a simple domain. Cuboid, one inlet (supply) one outlet.

Isothermal, Ke and incompressible.

I am trying three things. No real joy.

To start with.

Path lines (set from interior (fluid)) gives a max rtd of 6.07 secs Particale tracks, (I set an injection of Carbon dioxide thoughout all fluid) gives 2.8 secs.

Why the difference?

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?

I get a uniform distribution of zero!

Ideas?

Thanks

Sorry Guys,

The RTD calc was meant for the fluent forum. Perhaps I now need a rest!