This thesis deals with the topic of simulating the hydrodynamics of microplastic particles. In the introductory part, the general properties of microplastics are described, and the mathematical modeling of the particles is presented. The theory of turbulent flow and different ways of its numerical modeling are also briefly discussed, considering that for the purposes of conducting the simulation, we first need to determine an adequate turbulent model. A description of the experiment is given, according to the results of which we later confirm the validity and precision of the simulation. The following chapters describe the creation of the domain and the numerical network, and the implementation of the simulation of water flow in an open channel, which we performed to select an adequate turbulent model, and the k-ω SST turbulent model was chosen. It was also necessary to simulate the flow of water in order to obtain the stationary flow that we use when simulating the flow of microplastic particles. The creation of the domain and the simulation were done in OpenFOAM, which is why the instructions for the above-mentioned software are given. The simulation of microplastic particles had to be done in a supercomputer environment, so the Bura supercomputer was used to solve the task, whose technical specifications and mode of operation are given in this thesis for that reason. Two types of particles of different dimensions were simulated, spherical and non-spherical, i.e. in this case, in order to compare the results, the non-spherical particles were cubical. The key quantities that were compared were drag coefficients and Reynolds numbers. It was shown that the results of the simulation of the flow of spherical particles match extremely well with the experimental results for the same, while for cubic, i.e. non-spherical particles, significantly worse results are obtained due to deficiencies in the code of the OpenFOAM solver.