I've been reminded of a technique for warming a transverse flute that almost certainly can't be applied to fipple flutes but is worth mentioning.

When I first met Bronnie Evans, she was a PhD student in biochemistry at the ANU and a red hot flautist; she played what classical musicians call a concert flute (silver, Boehme system I suspect, rather than the "Simple system" favoured by the Irish and called by them a concert flute) and had recently picked up tin whistle. At the Kapunda Celtic Music comp. she stunned everyone with how her flute filled the hall with liquid sound; her teacher was a clarinettist who concentrated on her intonation and it showed.

Her technique for warming the instrument involved, as I recall, controlling the embouchure and overblowing hard enough to produce ultrasounds, ie above the normal frequencies heard by us humans. I watched her embouchure closely, as I was a bit sceptical, but it was different from the usual versions she used while playing and the body of the flute appeared warmer to the touch.

Bronnie later turned her attention to Macedonian kaval and was so good she was given a lovely pair made specially for her by a visiting Macedonian expert whose name I forget; their bores were kept clean and moisture-free by the paired rods on which the kavals were stored. Australian folk music lost a great talent when she concentrated on the careers as a research biochemist (at which she has been extremely successful) and a wife and mum (which presented extremely taxing responsibilities) and used classical piano (in private) as her only musical outlet.

Cheers, Rowan