July 20, 2020 at 8:39 amWeaerodoSubscriber
I need to calculate the Age of Air
From the manual I got the udf of diffusivity as follows
real source = C_R(c,t);
when I have utilised this udf, by creating a scalar and solving it
I am not sure about the results, are the units in seconds??
because I don't think 7 seconds will be the right answer as the domain is larger.
Apart from this, I have created an injection (massless), and from post-processing, I have calculated the residence time
I was getting the residence time as 1061 seconds.
Please suggest me regarding this.
July 20, 2020 at 8:40 amDrAmineAnsys Employee
July 20, 2020 at 3:57 pmRobAnsys Employee
What materials are you using?
July 20, 2020 at 4:39 pmWeaerodoSubscriber
Do you feel my result is appropriate.?
Is there a difference between the residence time and age of air?
July 20, 2020 at 4:41 pmWeaerodoSubscriber
The material is air, the density is an incompressible ideal gas.
Is there anything??
Are you feeling doubtful about the result?
July 21, 2020 at 3:32 pmRobAnsys Employee
How well converged is the scalar? As I don't know the size of the domain I have no idea if it's correct.
July 22, 2020 at 11:17 amDrAmineAnsys Employee
If you do not trust your results you might inject a massless particle and check its residence time. We do not know your case, domain extension and boundaries used here so we cannot comment on unknown things.
July 22, 2020 at 2:20 pmWeaerodoSubscriber
Thanks for your responses.
I understand I should have specified a few details about the domain.
The domain is 4*2.5*3 (meters).
Yes, Injection of a massless particle is giving me a value of 1061 seconds, whereas the scalar was giving me 7 seconds.
Should I go with the injection? (I wonder what was my mistake for the scalar case.!)
July 22, 2020 at 2:35 pmDrAmineAnsys Employee
No no : check the particle tracks perhaps you have a particle stuck somewhere which is not really what you want to have. Do you have inlet /outlet? More details please........ And what value you have at inlet for your UDS...?
July 22, 2020 at 3:07 pmWeaerodoSubscriber
I have two inlets and two outlets.
The uds is specified a value = 0 at the inlets (Blue colour in the contour), whereas for all the remaining boundaries I have selected the flux=0.
Apart from these things, is their any other important thing to consider while solving for the scalar.?
Do we need to add source in the cell zone?
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