LSMS (Liquid Spill Modelling System) is a tool for calculating the spreading and vaporisation of a liquid pool.
Liquids such as liquefied natural gas (LNG), liquefied petroleum gas (LPG) and others are routinely stored at low temperatures and on their release to the atmosphere they boil or evaporate depending on their temperature relative to the ambient air. Such liquids flow across the ground or other substrate surrounding the containing vessel, extracting heat from the underlying surface which provides the energy to drive the vaporisation. As the liquid spreads, the size of the liquid pool changes and the vaporisation rate alters accordingly and such information is essential for calculating the subsequent dispersion of the cold vapour. In many circumstances the containing vessel is surrounded by some mitigating measure such as the presence of a bund and the flow of the liquid and its interaction with the bund wall presents a formidable prediction problem.
LSMS development was sponsored by BG, Gaz de France, the US Gas Research Institute and the UK Health and Safety Executive. It has been used by those sponsoring organisations and also by CERC and other consultancies.
As a one-dimensional shallow-layer model, LSMS can model spreading and vaporisation of liquid spills in more detail than an integral model. It solves the hydrodynamic shallow-layer equations in one (x or r) dimension and includes interaction with a vertical retaining bund wall, including overtopping and further spreading of liquid beyond the bund. It allows a solid, porous or liquid substrate. Its thermodynamic equations incorporate a unified treatment of cryogenic and volatile liquids.
LSMS output can be used with GASTAR to allow straightforward study of dispersion of the vapours that emanate from the pool. LSMS output can also be used as input in other dense gas dispersion models.