When you blow out a candle, what precisely is responsible for extinguishing the flame? Oxygen deprivation? Thermal loss due to convection? Halitosis?
I don’t know the answer for sure, but I’ll gladly throw out a WAG.
By blowing on the candle, you’re forcefully displacing the gaseous fuel (in this case, candle wax vapor) from the area immediately around the wick. Thus, the oxygen/fuel ratio is pushed past the point where combustion is possible, and the self-sustaining process is halted.
The thermal convection idea you threw out is not far from my guess above. But I would think your breath couldn’t cool the wick off fast enough to stop the wax from vaporizing. Heat loss doesn’t explain the instant disappearance of the flame. Besides, after you blow a candle out with a quick puff, the wax usually still vaporizes, and you can see the smoke still streaming from thw wick. Which means it’s still hot enough to supply fuel even after being extinguished.
I believe that blowing does reduce the immediate heat from the combustion reaction to a temperature below which it is not independently sustainable.
If the puff of breath were removing oxygen from the reaction and not removing heat, then the candle could re-ignite when resupplied with 21% oxygenated ambient air, which would happen almost immediately.
The fuel source is still there-hold a match next to the smoke plume from a freshly extinguished candle, and the flame will leap back to the wick.
Hmm. . . so your theory is that essentially you’re scattering the fuel source (wax vapor) to the four winds. But you can also blow out a match, which doesn’t depend on a gaseous fuel source to burn (does it?).