Buoyancy-induced flow

[TheZed]

Hi,
I am rather new to IES. I have checked this forum and have scrutinised the software but, somehow, I am unable to model buoyancy-driven flows. I can simulate normal flows (which would include buoyant and wind-related forces) using two openings; and I am even getting reverse flows for periods when outside air is hotter than inside air. This is normal for buoyant flow so my model is more or less set up correctly. The problem now is, I would like to model the flow of air due to temperature differennce between interior and interior ONLY. Without the imapct of wind, that is.

How do I go about this please? Any help will be greatly appreciated.

TheZed

[JosephG]

You should probably read the MacroFlo Calculation Methods manual. IES does calculate buoyancy driven flows, but depends a lot on which type and how your model is setup. What do you mean by internal buoyancy flows, vertical or horizontal flow? Within the same typical height room or within an atrium / multi-story room?

[TheZed]

I am referring to simple airflow as a result of difference in temperature between interior and exterior (buoyancy). Natural ventilation works with one of two forces (a) Wind (b) buoyancy; or a combination of both. Sometimes, it is necessary to design ventilation to work with buoyancy only. This is what I wanted to do, as wind in my case is regarded as unreliable. After many weeks/months, I found that there is a way to create buoyancy driven flow in IES. Many thanks to my supervisor.

You need to:
1. Go to > Macroflo > Macroflo Opening Database Manager
2. Select your project openings (e.g. inlets, windows, shafts) from 'Macroflo Opening Types' (i.e. left panel)
3. Under 'Exposure Type' dropdown menu, select > '00.Internal'. This should the first option in the dropdown list by the way.

Selecting this exposure type for ALL your openings will ensure that they (openings) neglect the effects of wind (speed/pressure). All airflow into the building will be based purely on temperature differential that exist. i.e. between interior temperature (internal gains) and ambient temperature.

That is modelling buoyancy-driven ventilation in 3 simple clicks using IES.

Hope this helps others. The folks at IES need some serious tutorials about ventilation modelling with IES.

cheers

TheZed