In fluid dynamics, Landau–Squire jet or Submerged Landau jet describes a round submerged jet issued from a point source of momentum into an infinite fluid medium of the same kind. This is an exact solution to the incompressible form of the Navier-Stokes equations, which was first discovered by Lev Landau in 1944 and later by Herbert Squire in 1951. The self-similar equation was in fact first derived by N. A. Slezkin in 1934, but never applied to the jet. Following Landau's work, V. I. Yatseyev obtained the general solution of the equation in 1950.