Modelling of ammonia emissions from naturally ventilated livestock buildings. Part 3: CFD modelling

The purpose of this review paper is to identify current capabilities of Computational Fluid Dynamics (CFD) modelling techniques and areas where further scientific research is required, in order to identify how best CFD can be utilised in the future as a comprehensive modelling tool that enables naturally ventilated (NV) livestock buildings to be designed to reduce ammonia emissions.The review indicates that CFD methods possess many of the elements needed to develop reliable models for prediction of ammonia emission (AE) from NV livestock buildings. Nevertheless, development and validation of methods to specify boundary conditions regarding the ammonia-emitting surface is still a challenging task. In addition further development and validation is needed of (1) methods to model the influence of the animals and the influence of varying weather conditions, (2) strategies on how to select the most appropriate turbulence model relative to the modelling application at hand and computational power available, (3) more advanced solar irradiation models to gain more understanding of its effect on AE, (4) standardised sensitivity analysis of the uncertainties involved in the CFD model, (5) standard approaches to the incorporation of contaminant transfer across boundary layers of emitting surfaces within large scale simulations, and (6) more effective meshing techniques.