  The electronic analog of the Poiseuille flow is the transport in a narrow
channel with disordered edges that scatter electrons in a diffuse way. In the
hydrodynamic regime, the resistivity decreases with temperature, referred to as
the Gurzhi effect, distinct from conventional Ohmic behaviour. We studied
experimentally an electronic analog of the Stokes flow around a disc immersed
in a two-dimensional viscous liquid. The circle obstacle results in an additive
contribution to resistivity. If specular boundary conditions apply, it is no
longer possible to detect Poiseuille type flow and the Gurzhi effect. However,
in flow through a channel with a circular obstacle, the resistivity decreases
with temperature. By tuning the temperature, we observed the transport
signatures of the ballistic and hydrodynamic regimes on the length scale of
disc size. Our experimental results confirm theoretical predictions.
