Grid fin in incidencel: the air flow passing through the cells is forced to adopt their direction. Here the cellular panel was placed in incidence by turning it in a horizontal plane. The wind, also horizontal, enters the cells with a biased direction. It turns out that the new orientation of the air flow takes place in the cells over a very short distance (this is why there is absolutely no need for the cells to be longer).
<a href="//commons.wikimedia.org/wiki/User:Bernard_de_Go_Mars" title="User:Bernard de Go Mars">Bernard de Go Mars</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>