Effect of chemical reactions on electrohydrodynamic force generation process in dielectric barrier discharge

A discharge plasma simulation based on a three-fluid model is generally utilized to understand the physical mechanism in a dielectric barrier discharge (DBD) plasma actuator. In this study, the influence of chemical reactions considered in a numerical model on the simulation results is investigated from the viewpoint of electrohydrodynamic (EHD) force generation in the DBD plasma actuator. Positive and negative streamers are simulated utilizing three types of models considering different reactions and species, and the investigation is conducted in two steps. In the first step, where the influence of the neutralization process is investigated, the electron recombination with a cluster ion (O4+) plays an important role; it contributes to the decrease in seed electron production and effective coefficient of ionization for the positive streamer, and the decrease in negative ion production for the negative streamer; as a result, the propagation length and EHD force generation decrease. In the second step, where the influence of the production process is investigated, the stepwise ionization from metastable states has little influence owing to quite low production rates. Therefore, the simulation results indicate that the numerical model needs to consider the electron recombination with O4+ to accurately predict the streamer propagation and EHD force generation, while it is unnecessary to take into account the metastable molecules.