  We have developed a realistic simulation of 2D dry foams under quasi-static
shear. After a short transient, a shear-banding instability is observed. These
results are compared with measurements obtained on real 2D (confined) foams.
The numerical model allows us to exhibit the mechanical response of the
material to a single plastication event. From the analysis of this elastic
propagator, we propose a scenario for the onset and stability of the flow
localization process in foams, which should remain valid for most athermal
amorphous systems under creep flow.
