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Old   September 21, 2006, 13:01
Default rel-humidity hvac
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I want to model (passive) pollutant dispersion, and relative humidity distribution in a HVAC simulation.

If I know the flux of water and pollutant from sources in the building and the relative humidity of the ambient air, how do I enter all this infomation as boundary conditions for the passive scalar equations of STAR-CCM+?

Also, Is there any reason for having access to only one passive scalar model per simulation in this software?

Thank you for helping! S
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Old   September 25, 2006, 14:20
Default Re: rel-humidity hvac
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Humidity distribution is one of the most important variable in HVAC and air conditioning. Instead of a passive scalar you can start with a field function in the form:

W = A(T)/P + B(T) where A and B are functions of temperature, P is pressure and W is the water content.

For example for building/room analysis:

If you have humidity below 25% some kind of germs develops If you are above 45% some other kind of bacteries gets in

The minimum bacterial/germs proliferation is around 35-40%.

Why not use an active scalar as the density of vapor is smaller than the one of air?

Some law can be found in the literature (journal, papers) and internet (search on google, yahoo)

If you contact your local support office may be they can forward you a test case or an example.

Good luck


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Old   September 26, 2006, 15:36
Default Re: rel-humidity hvac
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Thanks Donald,

Should I have small inlets (e.g. on top of persons head) in the domain issuing this water and pollutant flux in the solution?

Is this whats generally done?

Thank you, Regards.
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