Hi there,
I have a situation where I'm trying to capture infiltration from a wind recirculation region in the leeward side of my building, created when wind strikes my building and creates a negative pressure zone on the leeward side. It doesn't seem like MacroFlo captures this behaviour very well, though I understand you can modify the Cp values. Any recommendations? Tx in advance!
Recirculation Regions
Re: Recirculation Regions
Mark,
I feel you are trying to capture a very complex phenomenon using a very simple tool. The way MacroFlo works, it sort of uses Bernoulli's principle to calculate the pressure on the windward side and the pressure on leeward side is sort of set to zero. This is a very simplistic explanation I am giving here but you should get the picture.
The coefficient of discharge of an opening have additional components based on angle of attack added on to them. These basically decide if the flow is going to go in or out the opening. depending on it's orientation to the wind direction.
You have to understand that ApacheSim is a steady state tool and the swirls are a distinctly transient phenomena. You can edit the properties of the openings by editing the appropriate files in the installation, but tread VERY VERY, VERY carefully.
You will need to determine by experimentation/ CFD simulations the coefficient of discharge for openings not only varying wind directions but also wind speeds. I am thinking at least 16 wind directions and may be 10 wind speeds each (that is a 160 CFD simulations at a minimum) You will then need to figure out a way to make sense of data and input in to MacroFlo.
I will not be surprised if you end up with the numbers already in MacroFlo.
So don;t worry about capturing a phenomena that lasts for a few seconds using a tool that reports the data on scale of a minimum of 10 minutes.
I feel you are trying to capture a very complex phenomenon using a very simple tool. The way MacroFlo works, it sort of uses Bernoulli's principle to calculate the pressure on the windward side and the pressure on leeward side is sort of set to zero. This is a very simplistic explanation I am giving here but you should get the picture.
The coefficient of discharge of an opening have additional components based on angle of attack added on to them. These basically decide if the flow is going to go in or out the opening. depending on it's orientation to the wind direction.
You have to understand that ApacheSim is a steady state tool and the swirls are a distinctly transient phenomena. You can edit the properties of the openings by editing the appropriate files in the installation, but tread VERY VERY, VERY carefully.
You will need to determine by experimentation/ CFD simulations the coefficient of discharge for openings not only varying wind directions but also wind speeds. I am thinking at least 16 wind directions and may be 10 wind speeds each (that is a 160 CFD simulations at a minimum) You will then need to figure out a way to make sense of data and input in to MacroFlo.
I will not be surprised if you end up with the numbers already in MacroFlo.
So don;t worry about capturing a phenomena that lasts for a few seconds using a tool that reports the data on scale of a minimum of 10 minutes.
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