  We observe a large negative magnetoresistance and a decrease of resistivity
with increasing temperature, known as the Gurzhi effect, in a bilayer electron
(BL) system formed by a wide GaAs quantum well. A hydrodynamic model for the
single fluid transport parameters in narrow channels is employed and
successfully describes our experimental findings.
  We find that the electron-electron scattering in the bilayer is more
intensive in comparison with a single-band well (SW).
  The hydrodynamic assumption implies a strong dependence on boundary
conditions, which can be characterized by slip length, describing the behavior
of a liquid near the edge. Our results reveal that slip length in a BL is
shorter than in a SW, and that the BL system goes deeper into the hydrodynamic
regime. This is in agreement with the model proposed where the slip length is
of the order of the electron-electron mean free path.
