  We report the experimental observation of dynamical behavior of flowing
complex plasma past a spherical obstacle. The experiment has been carried out
in a $\Pi$-shaped DC glow discharge experimental device using kaolin particles
as the dust component in a background of Argon plasma. A stationary dust cloud
is formed by maintaining the pumping speed and gas flow rate. A spherical
obstacle vertically mounted on the cathode tray acts as an obstacle to the flow
of dust particles. The controlled dust flow is generated by reducing the mass
flow of the neutrals through a mass flow controller. The flowing dust particles
are repelled by the electrostatic field of the negatively charged sphere and a
microparticle free region (dust void) is formed surrounding the obstacle. The
far particles are attracted towards the floating obstacle and reflected back
when they have arrived at a minimum distance, causing a ring shaped structure
around the obstacle. We characterize the shape of this structure over a range
of dust flow speeds and obstacle biases. For a supersonic flow of dust fluid
around a negatively biased obstacle, a bow shock is formed on the upstream side
of the sphere, while the generation of wave structures is observed on the
downstream side for a particular range of flow velocities. Reynolds numbers in
this case is estimated as $R_e \gtrsim 50$. This wave structure reminds of the
beginning of the formation of a Von-K\'arm\'an vortex street. A physical
picture for the observed structure based on ion-drag, neutral streaming and
electric forces is discussed.
