  We present high resolution simulations with RAMSES of supersonic colliding
stellar winds. The collision results in a double shock structure which is
subject to different instabilities. The Kelvin-Helmholtz instability (KHI)
introduces some mixing and variability. For isothermal winds, the Non-linear
Thin Shell Instability violently affects the interaction region. Properly
modelling these instabilities requires a high enough resolution and an adapted
numerical method, especially when one of the winds strongly dominates the other
one. At large scale, orbital motion is expected to turn the shocked zone into a
spiral but we find that in some configurations the KHI may disrupt the spiral.
A colliding wind structure is also expected in gamma-ray binaries composed of a
massive star and a young pulsar which emits a highly relativistic wind.
Numerical simulations are necessary to understand the geometry of such systems
and should take into account the relativistic nature of the pulsar wind. We
implemented a second order Godunov method to solve the equations of
relativistic hydrodynamics with RAMSES, including the possibility for Adaptive
Mesh Refinement. After a brief overview of our numerical implementation, we
will present preliminary simulation that contrast the structure of the flow in
gamma-ray and stellar binaries.
