Two-way perturbative coupling of plasma–fluid interactions

Abstract This contribution focuses on the modeling of ionic wind generated by a stationary corona discharge (CD) within a steady imposed external flow. The electro-drift velocity of unipolar charges in air is generally of a few hundred meters per second, whereas ionic wind flow velocity is of the order of a few meters per second. For this reason, the influence of fluid advection is generally neglected in this context, resulting in a one-way coupling of the charges’ influence onto the flow, driven by Coulomb forces. Nevertheless, when considering an adverse fluid velocity larger than 10 m s −1 , this approximation fails and a two-way coupling arises between the charges’ drift and the fluid flow, which is more difficult to address numerically. Developing a previous asymptotic multi-scaled two-domain approach, we hereby propose a new perturbative two-way coupling method based upon the non-dimensional number M m , which is the ratio between the macroscopic electrically-induced ionic wind velocity to the microscopic drift velocity of charges. This approach predicts a near-linear dependence of the current with velocity, which is successfully compared with recent experimental measurements. Furthermore, it is shown and illustrated in various configurations how the electric field’s lines are deformed by the external flow, leading to a significant shrinkage of the collected charges’ region with increasing external velocity. The relevance of these findings for electro-precipitators is discussed.