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atwhaley / cfast

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Single vent versus multiple but equivalent vents give different answers #79

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
About 5 years ago I did a large number of sensitivity cases on vent
configurations. One thing I noticed was that the results were a little
different for a single H X W vent versus n (H X W/n) vents, all other inputs
being the same and the vents all having the same base height. The difference
seemed more than numerical, and there was no apparent cause in the model
theoretical development that I could find. I had brought this to you
attention at the time, so maybe you already checked into this.

Original issue reported on code.google.com by cfastdev@gmail.com on 10 Jan 2012 at 7:41

GoogleCodeExporter commented 9 years ago 
Although the vent flow itself is just a function of area, the doorway mixing is 
a non-linear funciton of the mass flow through the vent so that two mass flows 
1/2 the magnitude will result in slightly different mixing, thus slightly 
different layer temperatures, thus slightly different flows, etc until a 
consistent solution is obtained.

Bottom line, they shouldn't be identical, but they should be close.

Original comment by cfastdev@gmail.com on 10 May 2012 at 7:29