  We prove non-existence of nontrivial uniformly subsonic inviscid irrotational
flows around several classes of solid bodies with two protruding corners, in
particular vertical and angled flat plates; horizontal plates are the only case
where solutions exists. This fills the gap between classical results on bodies
with a single protruding corner on one hand and recent work on bodies with
three or more protruding corners.
  Thus even with zero viscosity and slip boundary conditions solids can
generate vorticity, in the sense of having at least one rotational but no
irrotational solutions. Our observation complements the commonly accepted
explanation of vorticity generation based on Prandtl's theory of viscous
boundary layers.
