• engulfment
• stability
• t-mixer
• unsteady

The simulation of the flow inside a T-shaped micromixer is carried out, aimed
at identifying the transition Reynolds number from steady to unsteady en-
gulfment regime, and at investigating the flow behaviour in the latter. The
characterization of the instability leading to the unsteady engulfment regime
is also conducted, through a three-dimensional linear stability analysis and
through the computation of the associated global eigenmodes. Finally both
the adjoint and direct modes are used to evaluate the sensitivity to arbitrary
base flow modifications. The information obtained can be used to identify
regions of the base flow that contribute to the onset of a periodic pulsating
regime within the micro T-mixer, and more generally may be the starting
point for future development of control strategies.