Smoke modelling is a technique for simulating the way smoke will behave in the event of a fire. In certain types of building, such as a shopping centre or a building with an atrium, smoke modelling is likely to be required as part of the standard design process. In others, it might be used as part of a fire engineering justification for a building (such as to justify extended travel distances). There are two main types of smoke modelling available, zone smoke modelling and CFD smoke modelling.
Zone smoke modelling is a technique that is based on equations derived from practical experiments. For the building that is being considered, as long as the physical geometry and possible fire scenarios are within the limitations of the fire tests that have been carried out, zone smoke models are a perfectly acceptable way to predict the likely smoke flow rates.
Zone models have the advantage that they are relatively simple and quick to carry out. However, if the building shape or fire scenario are outside the limits of the experiments that were carried out, zone models cannot be used. They are therefore only useful in certain specific situations, but in those situations they give quick, simple and accurate results.
CFD smoke modelling is a very different approach. The basis of the technique is that the space that is to be modelled is built into a computer program, which breaks the space into a large number of individual cells (typically hundreds of thousands). The computer program then uses fundamental laws of physics and fluid flow to analyse the flow of the air and smoke between each cell for the duration of the fire.
CFD analyses take longer than zone models to set up within the computer simulation, and each analysis can take several days to run, even on high specification computers. However, they can analyse smoke flow in a much wider range of scenarios than are possible by using zone models.
CFD takes considerable experience to use correctly, and this experience has been built up at ASEC over many years. Some examples of projects where CFD has been employed include large atria spaces, exhibition halls and car parks.
ASEC engineers includes experts in all types of smoke modelling in all types of buildings.