LES modelling of hydrogen release and accumulation within a non-ventilated ambient pressure garage using the ADREA-HF CFD code N. Koutsourakis a,b, *, A.G. Venetsanos a , J.G. Bartzis b a Environmental Research Laboratory, NCSR Demokritos, Aghia Paraskevi 15310, Greece b Department of Mechanical Engineering, University of West Macedonia, Kozani 50100, Greece article info Article history: Received 2 March 2012 Accepted 27 May 2012 Available online 26 June 2012 Keywords: CFD Large eddy simulation Hydrogen safety Garage Confined space ADREA-HF abstract Computational Fluid Dynamics (CFD) has already proven to be a powerful tool to study the hydrogen dispersion and help in the hydrogen safety assessment. In this work, the Large Eddy Simulation (LES) recently incorporated into the ADREA-HF CFD code is evaluated against the INERIS-6C experiment of hydrogen leakage in a supposed garage, which provides detailed experimental measurements, visualization of the flow and availability of previous CFD results from various institutions (HySafe SBEP-V3). The short-term evolution of the hydrogen concentrations in this confined space is examined and comparison with experimental data is provided, along with comments about the ability of LES to capture the transient phenomena occurring during hydrogen dispersion. The influence of the value of the Smagorinsky constant on the resolved and on the unresolved turbulence is also pre- sented. Furthermore, the renormalization group (RNG) LES methodology is also tested and its behaviour in both highly-turbulent and less-turbulent parts of the flow is highlighted. Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Given the shortage of fossil fuel and the environmental concerns from their use, hydrogen’s special characteristics as an energy carrier have attracted the interest of the scientific community in recent years [1]. Indeed, in Europe for example, hydrogen and fuel cells are the first research topic of the 2.35 billion euro non-nuclear energy budget of the 50.5 billion euro total Seventh Framework Programme funds [2]. This trend reflects both the high potential of hydrogen energy and the safety concerns from its possible generalized use. Hydrogen used in transportation has 2.5 times the energy efficiency of improved gasoline vehicles [3], being at the same time renewable and environmentally friendly, especially if clean energy is used for its production [4]. On the other hand, hydrogen is colourless, odourless, very buoyant under atmospheric conditions, with a wide flam- mable range between 4 and 75% by volume, a low ignition energy and a relatively high burning velocity, making its storage and handling hazardous and challenging [5]. On those grounds, the understanding of potential acci- dental release in a garage, as well as the ability to model it, is of particular importance and has attracted both experimental and numerical CFD studies [6e20]. The numerical studies [8e20] resulted in the conclusion that CFD is a convenient means for examining hydrogen dispersion and can provide reasonable agreement with the experimental data. CFD is indeed a very strong and relatively low-cost tool that can help in exploring various hydrogen dispersion scenarios and support not only design procedures, but also decision * Corresponding author. Environmental Research Laboratory, NCSR Demokritos, Aghia Paraskevi 15310, Greece. Tel.: þ30 2106503408; fax: þ30 2106525004. E-mail addresses: nk@ipta.demokritos.gr, nkoutsourakis@uowm.gr (N. Koutsourakis). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 37 (2012) 17426 e17435 0360-3199/$ e see front matter Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2012.05.146