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Modeling atmospheric dispersion of flammable and toxic gases is very common in the industry. There is a large spectrum of different models, from Gaussian, Integral, up to computational fluid dynamics (CFD) models. However, these simple engineering models (Gaussian, Integral) do not always correctly estimate the dispersion of gases with a density higher than air. The purpose of this paper is to present an alternative/new model Ventjet dedicated to the atmospheric dispersion of various gases, including light gases (hydrogen, methane, etc.), neutral gases (nitrogen, oxygen), and heavy gases (CO2, LNG, etc.). Ventjet takes into account various weather condition profiles, namely neutral D and stable F. The effect of the ground is also integrated into Ventjet. Ventjet can be used for various releases, including vertical, angled, and even into the wind. Ventjet has been broadly validated versus multiple measurements from wind tunnel and field experiments, as well as CFD simulations. [ABSTRACT FROM AUTHOR]

In this paper, the convergence behaviour of the method of auxiliary sources (MAS) is studied in cases of simple three-dimensional (3D) problems with open regions. For the assessment of the convergence behaviour in such cases in a general manner, the cases considered herein consist in elemental electric dipoles radiating in the close proximity to a planar dissipative ground. Both vertically and horizontally oriented dipoles with respect to the ground plane are examined. The aim of the study is to investigate the interrelation between the auxiliary sources locations and the resultant field continuity errors. For this, the dependence of the boundary conditions errors on the number and spacing of the auxiliary sources is exhibited and general rules regarding their behaviour are extracted. Moreover, the influence of these errors on quantities of interest is examined. Finally, a few concluding remarks are outlined and their possible utilization in cases of more composite 3D problems is discussed. Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the convergence properties of the method of auxiliary sources (MAS) when applied to two-dimensional (2D) problems with open boundaries are studied. Although such problems have been examined in the past, the relation of the solution errors with the sources' locations has not been reported in detail. Herein, the convergence behavior in the case of a single infinite wire above a flat ground is thoroughly examined. The dependence of the boundary-condition errors on the number and spacing of the auxiliary sources is illustrated and general rules that govern their behavior are extracted. Finally, a few concluding remarks are outlined and their utilization for the advancement of the MAS is briefly discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 518–522, 2003 [ABSTRACT FROM AUTHOR]