Airflow problem

[robboffard]

(Mods, if I haven't posted this in the right place, please move it!)

 

I'm terrible at physics, so I'm hoping to get some help from this forum.

 

I have a fibreglass cast on my right arm, courtesy of a stupid skateboarding accident. I have devised a method for aerating the cast, which can become a bit stinky. My method involves a vacuum cleaner and an improvised nozzle, consisting of foam rubber pipe insulation with a gauge of 1/2".

 

It works well - the seal is relatively airtight against the cast itself, and I can feel it sucking air through the fibreglass. However, I'd like to improve it further.

 

Assuming the above gauge (1/2"), a variable length (currently 5 inches, but I can cut longer or shorter lengths) and a constant suction rate from the vacuum, how would I improve the airflow? Would investing in a larger-gauge 'nozzle' increase or decrease the effectiveness?

 

For further info, the cast consists of fibreglass plaster on top of cotton padding and a single layer of bandages, of an average thickness of, I'd guess, 1/8". The cast is new, and there has been minimal muscle atrophy, so there is not a lot of space between my skin and the cast itself. The cast is perhaps a foot long, from the base of my fingers to just below my elbow.

 

Happy to provide any further info needed. Thanks guys!