Simulating coastal engineering processes with OpenFOAM® Pablo Higuera, Javier L. Lara, Inigo J. Losada ⁎ Environmental Hydraulics Institute “IH Cantabria”, Universidad de Cantabria, C/ Isabel Torres n o 15, Parque Cientifico y Tecnologico de Cantabria, 39011, Santander, Spain abstract article info Article history: Received 26 February 2012 Received in revised form 3 June 2012 Accepted 6 June 2012 Available online 19 July 2012 Keywords: CFD OpenFOAM Two phase flow Wave breaking Run up Undertow current In the present work, the OpenFOAM® newly developed wave generation and active absorption boundary condition presented in the companion paper (Higuera et al., submitted for publication) is validated. In order to do so the simulation of some of the most interesting physical processes in coastal engineering is car- ried out and comparisons with relevant experimental benchmark cases presented. Water waves are found to be generated realistically and agreement between laboratory and numerical data is very high regarding wave breaking, run up and undertow currents. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The main purpose of the present work is to validate OpenFOAM® as a tool to simulate a great number of relevant physical processes in coastal engineering. This is the second part of a paper in which wave generation and active absorption in a three-dimensional scenario were introduced as a first step to generalize the use of OpenFOAM® to the coastal engineering field (Higuera et al., 2013-this issue). The re- sults shown could have not been reproduced to the presented degree of accuracy without such developments. In order to validate the model, several well-known experiments are replicated and in some cases fur- ther analysis is obtained from the numerical results. The simulated pro- cesses include wave breaking, the interaction of a long wave with a transient wave group, the rip current development in a 3D beach, wave induced run up or the effect of bottom friction. The use of Reynolds–Averaged Navier Stokes (RANS) equations to model coastal engineering processes is growing in importance. One of their greatest features is the capability to obtain three dimensional pressure and velocity profiles, which allow for a more realistic treat- ment of all the dynamics, being capable of accurately simulating wave conditions along the whole spectrum of relative water depth. Their continuous Eulerian approach makes it easier to track magni- tudes in any point of the mesh. SPH models (Dalrymple et al., 2010; Shao, 2006), which follow a Lagrangian approach, have to address the inherent discontinuity between individual particles. Although the results are very promising, the models are still in an early stage of validation for real applications. Additionally, the RANS equations are solved without further assumptions, which is an advantage in comparison with Boussinesq models or other wave theories, for which wave breaking process must be triggered artificially (Liu and Losada, 2002). The principal drawback of RANS approach is that it is highly computationally demanding. The practical applications of RANS are huge. Some of them were introduced in the first part of this paper (Higuera et al., 2013-this issue), from which Lubin et al. (2003), Li et al. (2004), Wang et al. (2009) or Lara et al. (2012) and del Jesus et al. (2012) are remarked. Several turbulence models have been considered in the present work. The κ − model has been initially considered as it is a widely used model. It has proven to be quite accurate to simulate shear flows in the free flow region. However, its performance appears to be poor near the walls, within the boundary layer region. Therefore, the κ −ω SST model has also been considered to account for such lim- itation. κ −ω SST had never been used for wave–structure interaction problems until del Jesus et al. (2012). This model was introduced by Menter (1994), and takes the best from κ − and κ −ω. This combi- nation makes use of the first one in the free flow region and the sec- ond one in the boundary layer region. Each of them performs well in their application zone, and in between a linear combination of both models is considered. This paper is structured as follows. After this introductory part, the validation cases are presented. First the three-dimensional free sur- face and pressure induced by a solitary wave interacting with an im- pervious obstacle on a wave flume are numerically simulated. Once the model performance to simulate accurate pressure profiles has been proven the next step to consider is wave breaking. In a first Coastal Engineering 71 (2013) 119–134 ⁎ Corresponding author. E-mail address: losadai@unican.es (I.J. Losada). 0378-3839/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.coastaleng.2012.06.002 Contents lists available at SciVerse ScienceDirect Coastal Engineering journal homepage: www.elsevier.com/locate/coastaleng