  We show that the spatio-temporal ElectroHydroDynamic (EHD) force production
in surface AC-Dielectric Barrier Discharge (AC-DBD) actuators is strongly
influenced by both the streamer regime during the positive phase and the
micro-discharge regime during the negative phase. Focusing on the spatial EHD
force profiles, we demonstrate that the ionic wind spatial distribution can
only be explained by the positive contribution of the streamer regime. The
location of maximum ionic wind is found to be directly linked with the maximum
elongation of the streamers at several millimeters from the exposed electrode.
In both positive and negative phases of the AC-DBD operation, residual
volumetric and surface charges once again linked to the streamer formation and
afterburn, result to a variety of positive EHD force zones which, when
time-averaged in one AC period, contribute to the generation of the
experimentally observed induced thin wall jet. Through a thorough elaboration
of our numerical results, we provide an illustrative explanation of the EHD
force spatio-temporal evolution, showcase the importance of streamers and
retrieve a correct representation of the ionic wind spatial profiles when
compared to experiments.
