The electrohydrodynamic force distribution in surface AC dielectric barrier discharge actuators: do streamers dictate the ionic wind profiles?

We show that the spatio-temporal electrohydrodynamic (EHD) force production in surface alternative current-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.