...can be usefull,when we think about windmills,so about this unseen phenomena:windflow.Usually we "thrash" it with a wing -shape propeller,or we "beat" the air as with a whip or a stick(inclined plane surfaces).It's a wildly or violently movement.A flag in the wind tells us more...and suggests to think about waves,so to move gently from side to side,as raised moving area of water ,esp. an the sea shore.In a short word:naturally(light,sound,radio waves,a.s.o.).Then,the question can be:grinding,crushing,beating or pumping,undulating,oscillating?What is the best manner to drag out most power from the same incident surface of a windflow?Sometimes ,the manner(s) is the way of living,thinking and understanding phenomena around us.All the Bests!/Alex
...is a question of manner,also.Let's think a moment about a main property of the air:elasticity,flexibility, springiness.His adaptability is so large,from a whisper to a thunder.We can stirr so easy waves on the surface of a quiet lake:small action,great reaction.Speaking ,we make this waves,also.Now,if we induce waves,due to the motion of the blades (see feather concept) of a windmill,have we the same(greater!?) reaction of the windflow?Is this reaction more important than of an usually wing-blade shape?A simple practical comparison can solve this seeming(for me...) dilemma.Art helps us of seeing things invisible.All the Bests!/Alex