In earlier work the three-dimensional time dependent fully compressible CFD code ADREA-HF was applied against large-scale LH2 release experiments in the vicinity of buildings. In the present contribution the ADREA-HF code is applied to simulate large-scale LH2 spill tests in open, unobstructed environment. A series of simulations were performed to investigate on the effects of the source model (jet or pool), the modeling of the earthen sides of the pond around the source and the inclusion of a contact ground heat transfer. The predicted hydrogen concentrations (by vol.) are compared against the experimental at the available sensor locations. In addition the predicted structure of the concentration field is compared against the experimental, which was originally derived from temperature measurements. Modeling the source as a two-phase jet pointing downwards, including the modeling of the earthen sides of the pond as a fence and the contact heat transfer to the ground gave the best agreement with respect to experimental behavior. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.