Age of Air and Source Conflict
 

Hi all,

I am doing an analysis in a carpark, and want to calculate age of air and CO concentration.

When I run the sim with both setup, I get the CO concentration but age of air doesn't seem to increase (or calcualate) and remains at essentially zero.

If I don't add the source term age of air calculates fine.

Ideas why the source prevents age of air?

Cheers,
Mike

Can you post your CCL?

See attached.

Thanks!

It looks like you have not set a source term properly. You have set the source term to "Density", this should be set to 1.0.

This post is useful: http://www.cfd-online.com/Forums/cfx...e-age-air.html
It worked for me on the benchmark example.

Hi Glenn,

Thanks for the advice. So the source term has to be constant (ie, 1) rather than density? Density is the input I got told to use by Leap (Ansys provider). Hmm.

On another note, what did you use to assess the CCL?

Cheers,
Mike

Are you sure you are referencing the Density correctly? In fact that is probably your problem - if the Density function is zero then nothing will happen.

I suspect that if you have an incompressible simulation then the density variable is not present. I am not sure about that, but I think that is the case.

The ANSYS guy is probably right, you probably do need to integrate density rather than a constant.

So write a CEL expression which defines the density for the material properties, and then use that variable for the source term.

That will be exactly it. I'm assuming the Source "Density" is for air at 25degC, but I have set a custom fluid to allow calculation of CO.

Ok... so how do I specify density for my material to use as a source term?

I've just tried a few things and what you have done works fine for me. I used the simple benchmark simulation with a variable composition mixture with both Density and a constant (1) as the source term factor. Both worked fine.

So I recommend you do the same and try to get the benchmark simulation working, as I can confirm it definitely does work for me. Then you can start debugging your simulation.

Yip, you're right. A simplified model worked for me with Density as well.

Well that's good, now at least I know it can work, and I've just got something muddled elsewhere!

Thanks Glenn!
Mike