Emflume instrumentation entertainment. from Steve Gough on Vimeo.
Wet your finger. Blow on it. You can sense the cooling.
Try it with a dry finger. You'll probably sense that, too. Feel the cooling?
Your body works to maintain 37 °C . Air moving past it at a lower temperature cools it, that's why you sense the cooling of your finger.
Science lit is full of "thermal anemometry" papers, and you can buy instruments that measure airspeed this way -- a body, usually very small, is heated to a constant temperature, and the power needed to do that is a measure of fluid velocity past it.
I'm calling our work "hot body velocimetry" because there isn't a name for it in the lit, not for water.
We need to measure velocity in our new Emflume, and in our Emriver models.
Getting bloodless instruments to work as well as fingers is not so easy. Stick your finger in moving water and you'll see.