[milani]

As an Iranian, this is the first time I hear about these windmills! Unfortunately, the only source of info about them is this National Geography video.

There is no exclusive page for them on wikipedia, but I could find how they work generally here: https://en.m.wikipedia.org/wiki/Panemone_windmill

[mattlondon]

That wiki page suggests that the sails are articulated? In the video these are very much fixed sails - looks like battens of woods lashed or nailed together so I don't think the sails themselves can turn.

I do wonder which way the prevailing wind is for those windmills though as they are surrounded by walls. The knee jerk reaction is that the wind comes "face on" but then surely there would not be a turning force if the wind blows on both sides of the axis equally (especially since the sails look to be fixed)

I did notice there was a small vertical slit on the back wall, which makes me wonder if the wind blows "sideways" and generates lower pressure by blowing over the slit, causing the sails to move.

[lancefisher]

I would guess the wind blows into the slit, driving just one side of the paddle.

[Jestar342]

Just watching the video shows how they work just the same as a water wheel does, except "on their side". The wall(s) erected around them are shielding one half of the windmill, thus there is wind flowing onto one side of the windmill only.

[mattlondon]

Hmm yes of course :) So in the videos we are seeing the "back" of the windmills.

[pjc50]

They look surprisingly similar to a modern vertical axis wind turbine, although without the "lift" shape to the blades.