I thought you guys might find this interesting/useful - it's a project that someone put together for measuring air-flow using an Arduino for output display. Lots of info on the theory as well as the practical stuff on building it.
https://hackaday.com/2017/11/04/measuri ... ac-system/
Measuring Airflow in an HVAC system
Originally posted at johnlsayers.com, topic 21293.