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-   -   [Indoor Air Quality]How do I calcauate "Age of Air (https://www.cfd-online.com/Forums/cfx/25700-indoor-air-quality-how-do-i-calcauate-age-air.html)

 Young April 21, 2008 16:44

[Indoor Air Quality]How do I calcauate "Age of Air

Dear my colleagues,

I'm looking for the method to calculate "Age of Air" for a small residence model in CFX 11.0.

Do you have any experience about air change efficiency?

How do I set up CFX-solve to calculate the age of air?

 Martin April 23, 2008 04:51

Re: [Indoor Air Quality]How do I calcauate "Age of

Hi,

you have to create a new variable e.g. age_of_air. Then the inlet condition for this variable is age_of_air = 0 and you have to create a subdomain for the whole domain and set a constant source term for age_of_air. Then you can calculate the air change efficiency and the local air change index as well.

If your simulation is already finished you can calculate the air change efficiency by freezing all variables. You just have to solve the new variable age_of_air.

Regards.

 Young April 23, 2008 13:18

Re: [Indoor Air Quality]How do I calcauate "Age of

Thanks Martin,

You mean,

First, I have to make a new variable with CCL? or where I can creat a new variable?

How do I set the age_of_air = 0 at inlet condition?

Thank you for your kind response.

 Martin April 24, 2008 03:31

Re: [Indoor Air Quality]How do I calcauate "Age of

Hi,

you can create an additional variable in pre. The unit is seconds. Then you have to activate the variable in your domain -> fluid models and you can set that an additional transport equation should be solved. Then you can set the inlet boundary condition for this additional variable.

Regards Martin

 Young April 27, 2008 00:16

Re: [Indoor Air Quality]How do I calcauate "Age of

Dear Martin,

Thank you for your kind response.

You said that I need to set an additional transport equation.

but I can find an transport equation for age of air.

Would you explain the equation more detail?

I appreciate your comment and idea

Regard,

Young

 Martin April 27, 2008 05:58

Re: [Indoor Air Quality]How do I calcauate "Age of

Hi, when you created the new variable, go to domain and there to fluid models and you can see that this new variable has appeared and you can choose that an transport equation should be solved for this variable. Then you can set inlet boundary condition and source term for this variable as mentioned before. You can also look in cfx help for additional variables and you will find more informations.

Regards Martin

 Young April 28, 2008 23:14

Re: [Indoor Air Quality]How do I calcauate "Age of

Dear Martin,