  We theoretically investigate the interaction and propagation characteristics
of two co/counter propagating Mach cones triggered by two projectile particles
moving with supersonic velocities in the same/opposite directions through a
dusty plasma medium. The Mach cone solutions are obtained by solving a model
set of fluid equations for a heavily charged dust fluid that includes the
contributions of the projectile particles in the Poisson equation. The density
profiles and velocity vector maps of the Mach wings show interesting structural
changes when they interact with each other and form patterns similar to
interference fringes. Compared to the co-propagating Mach cones, the wings of
counter propagating Mach cones produce a larger number of maxima and minima in
the pattern resulting from their mutual interaction. In addition the time
duration of the formation of two maxima or minima at a particular point
decreases due to the interactions of Mach cones. Another notable feature is
that the spacing between adjacent maxima increases while the fringe angle
decreases with the increase of relative velocity of the counter propagating
projectile particles.
