The following paper considers the influence of acoustic oscillations on multiphase flows on their suspended particles, which can be destroyed or coagulated by vibrations. Considering this, the method of extension of application range of the dynamic separation element as vibrocoagulants due to the use of hydroaeroelasticity phenomena, namely flutter, has been proposed. There were considered the problems of development an engineering method for calculating dynamic separation elements, the main of which is the analytical solution of the hydroaeroelasticity problem. This work takes the first step to its development, considering the previous elastic elements deformation that has a significant effect on the flutter frequency. The state of their static equilibrium was conducted with the use of analytical dependencies of the finite element method. The bimodal finite elements with six degrees of freedom were used for dynamic deflection elements. As the result, there was determined the stiffness of pre-deformed plates and their maximum and minimum possible deflections. The functions of the median surface deflection in the form of a cubic polynomial were used in the model.In particular, there were considered the peculiarities of numerical modelling of coupled problems of gashydrodynamics flows and structural dynamics using the ANSYS Workbench, namely Fluent Flow and Transient Structural modules, which are combined with System Coupling. Also, the peculiarities of different approaches to multi-phase flow modelling are indicated. They are interesting not only by distribution of particles in the stream core, but also by the entrapped liquid film motion on the deposition surfaces.