A comparison of the steady-state electrohydrodynamic (EHD) flows structure in the needle-plane electrode system is carried out on the basis of the computer simulation results for injection and dissociation models of charge formation. The numerical computations of the EHD equations are performed with the software COMSOL Multiphysics 3.5 based on the finite element method. Part of the data obtained in the simulation is compared with the experimental ones to confirm the correctness of the proposed simulation method. Characteristic features of the flow structure are revealed for each mechanism of charge formation and some recommendations on the liquid choice for applied EHD device based on the discovered structure are given.