The results of methodical investigation, aimed on testing of the performances of free opensource CFD toolbox OpenFOAM in the field of simulation of hydraulic units’ dynamics using Finite Volume Method and dynamic meshes are presented. The following key features are reviewed: the choice of appropriate algorithms managing dynamic sliding meshes; design of the model case for the FSI-problem of interaction between a moving regulating element (plunger) and power fluid; plunger dynamics simulation for the prototype of the flow rate
regulator of new design; transient analysis of regulator’s internal flow; analysis of stability and computational efficiency. As the example simplified axisymmetric regulator model with incompressible power fluid is considered. The main steps of model case preparation are described. The model case is designed to simulate the problem of plunger equilibration under hydrodynamic forces and spring reaction. Results are given also for a preliminary steady-state simulation with fixed plunger, they have been used as initial conditions. Detailed description is given for the methods of mesh motion simulation, which follows plunger, as well as technology of sliding meshes (GGI), used for the piston throttle hole overlapping. Results are given for transient simulation: velocity, pressure fields, forces graphs, acting on the plunger, its displacement over time. The mechanism of jet streams and vertical flows creation in regulator’s flow channel is described. Methodical investigation, held in this paper, confirms that OpenFOAM in the “extend” version can be successfully used as an alternative for commercial CFD codes, as it contains all necessary tools to create and simulate cases incorporating dynamic meshes. It provides means for simulation of transient problems of hydraulic units which have moving parts.