Abstract—Nowadays, ocean energy has attracted more attention among the researchers due to its massive energy potential. As designing, constructing and testing prototypes are both expensive and time consuming, recently, many researchers have developed numerical wave tanks to simulate the behaviour of the waves as well as the interaction of waves with wave energy converters. This paper aims to model numerical wave tanks, using waves2Foam - a solver within OpenFOAM, to show the propagation of waves, as well as different wave breaking types. Firstly, a flat-bottom wave tank is modelled in order to simulate both generation and absorption of the waves. Such results are benchmarked against laboratory experiments data and the comparison between simulation and experiment results showed a good agreement. Furthermore, some additional cases are modelled to assess the capability of waves2Foam in absorption of waves’ reflection from the outlet boundary. Secondly, different sloped wave tanks are modelled to investigate the capability of waves2Foam in properly simulating wave breakings. Results demonstrated that waves2Foam is not only able to well simulate wave generation and absorption but it is also able to simulate all types of wave breaking. This work presents waves2Foam as powerful toolbox which can properly model waves based on different wave theories. However, some limitations of the solver were identified. Index Terms—Breaking waves, numerical wave tank, OpenFOAM, relaxation zone, Stokes wave theory, waves2Foam. I. INTRODUCTION Pollutant depletion and global warming caused by consumption of fossil energies have led researchers to find sustainable alternatives. Nowadays, renewable energy has become the top priority in most developed and some developing countries. There are various types of renewable energy with different capacity all over the world. In recent years, as wave energy has the highest potential in comparison with other renewables, it attracts more attention among the researchers and research institutes. However, there are still some technical issues and barriers which are required to be solved in order to get the real wave power. It is definitely crucial to design and construct sturdy wave energy converters which can cope with the harsh condition of the oceans [1]. In the past, wave studies were based on experimental and physical models which were both time and cost consuming. Today, due to improvement and development of powerful computers and computational methods, numerical models are mostly used. Recently, many researchers have developed their Manuscript received April 21, 2014; revised July 2, 2014. The authors are with the University of Coimbra, Department of Mechanical Engineering, Polo II, 3030-788 Coimbra, Portugal (e-mail: behrang.chenari@student.dem.uc.pt, shivasaadatian@student.dem.uc.pt, almerindo.ferreira@dem.uc.pt). numerical wave tanks to simulate ocean waves [2]. Numerical models are still under development in order to become an appropriate alternative for laboratory experiments. Numerical models are in fact mathematical models that use some sort of numerical time-stepping procedure (in transient studies) to obtain the models’ behaviour over time. Numerical modelling is a powerful method of predicting and visualizing the dynamic behaviour of physical systems. Computational fluid dynamics (CFD) software uses simplified equations but they will speed up the research as well as making it easier to study behaviour of wave and its behaviour when interacting with floating devices, sloped sea bed and also shore-based devices. Open Field Operation And Manipulation, known as OpenFOAM, is an open source computational fluid dynamics package of C++ libraries and codes that are created to conduct numerical modelling of solid and fluid mechanics problems and it was first released in 2004 [3]. OpenFOAM is distributed with a large number of solvers and utilities to cover a wide range of problems. However, it is possible for users to write their own codes and solvers for their specific problems or to modify the existing solvers due to the open source nature of OpenFOAM. Waves2Foam is a toolbox recently developed by OpenFOAM users to simulate free surface wave generation and absorption [4]. A relaxation zone technique known as active sponge layer has been applied to the library as well as a large range of different wave theories. The base of this toolbox is interFoam while an active sponge layer zone defined as relaxation zone method has been added to the solver. II. GOVERNING EQUATIONS AND WAVE THEORIES There are various types of wave theories, as [5] introduced and explained them but Navier-Stokes equations are basically used by OpenFOAM which are described as below: 2 2 2 2 2 2 x u u u u p u u u P u v w pg t x y z x x y z (1) 2 2 2 2 2 2 y v v v v p v v v u v w g t x y z y x y z (2) 2 2 2 2 2 2 z w w w w w w w w u v w g t x y z z x y z (3) where represents density in [kg.m-3], represents time in [s], p represents pressure in [Pa], g represents acceleration Numerical Modelling of Regular Waves Propagation and Breaking Using Waves2Foam B. Chenari, S. S. Saadatian, and Almerindo D. Ferreira Journal of Clean Energy Technologies, Vol. 3, No. 4, July 2015 276 DOI: 10.7763/JOCET.2015.V3.208