  The outflow of an object traveling in a fluid can shape the fluid morphology
by forming a forward bow shock which accelerates the object via gravitational
feedback. This dynamical effect, namely "dynamical anti-friction", has been
studied in idealized infinite uniform media, which suffers from the convergence
problem due to the long-range nature of gravitation. In this work, we conduct
global 3D hydrodynamic simulations to study this effect in the scenario of a
binary system, where the collision of outflows from both stars creates a
suitable configuration. We demonstrate with simulations that a dense and slow
outflow can give rise to a positive torque on the binary and lead to the
expansion of the orbit. As an application, we show that binaries consisting of
an AGB star and an outflowing pulsar can experience $\sim 10~\%$ orbit
expansion during the AGB stage, in addition to the contribution from mass-loss.
We also prove that the gravitational force drops as $O(r^{-3})$ from the center
of mass in the binary scenarios, which guarantees a quick converge of the
overall effect.
