Exponential growth of computational power in the past decade on one hand and the success of numerical models in studying hydro-environmental flows on the other hand lead to an increasing usage of this technique in hydraulic engineering problems. In particular, three-dimensional numerical models are becoming the industry standard, especially in problems where capturing three-dimensional flow characteristics are important. Additionally, with availability of open-source computational fluid dynamic (CFD) codes, this type of modelling is more accessible. Among these codes, OpenFOAM (Open Source Field Operation and Manipulation) is a state-of-the-art CFD code with an extensive range of features for engineering and scientific applications. In this paper, selected studies are presented which the authors carried out using OpenFOAM. These studies include a wide range of applications from implementation of the new algorithms to modelling a practical application in hydraulic engineering.