# A Review of Modelling and Simulation Methods for Flashover Prediction in Confined Space Fires
## 2 Modelling and Simulation of Flashover Phenomenon
### Flashover Simulation  
Previously, the problem of obtaining real data from this phenomenon and the possibility of using synthetic data if neural networks want to be applied to make a prediction has been commented. In this section research in this line is reviewed including those in which the flashover phenomenon has been simulated. Confined fires have been extensively studied by the fire science community in order to improve numerical modelling techniques. Research oriented towards improving fire extinguishing systems, personal safety or material behaviour can be consulted among others. Related with flashover, full scale experiments are expensive due to the high quantity of materials and facilities involving. In addition to that they are very polluting for the environment, therefore most of these studies has been carried out in small structures. Subsequently, different numerical models were developed to have a deep knowledge of fires, having special relevance the application of computer simulation techniques. Furthermore, the information about real situations related to flashover phenomenon is very poor. Not all fire services document this kind of emergencies sufficiently and there are problems to obtain technical data related with real cases of these emergencies. Different scenarios can be simulated by varying enclosure and combustion parameters, number and dimensions of vents and environmental conditions. However, fire simulations must be employed in a responsible and acceptable way and users must have knowledge of the model and fire behaviour [37]. After evaluating different existing techniques related to fire simulation (algebraic correlations, two Zone Models or Lumped Parameter Models [38] and CFD or Field Models) we have considered to review in this article the CFD models. Field Models approximate a space as a large number of discrete volumes. Furthermore it is capable to simulate complex confined fires scenarios and high quantity of research has been carried out to validate different CFD models. Considering the time spent to perform the simulations, most of the studies reviewed in this paper have used computational fluid dynamics techniques for their research including large eddy simulation (LES) technique (e.g., [30; 39]). LES has the capacity of reducing the computational cost by ignoring the smallest length scales, which are the most computationally expensive to resolve, via low-pass filtering of the Navier-Stokes equations and to capture essential time-resolved information. Fire chemistry and soot formation and combustion processes has to be resolved to complete the fire model. CFD software gives the possibility to obtain similar structured data to that of a vision thermal camera. For this reason and given its simulation accuracy the most relevant researches using this technology is reviewed in this section. Much research has been carried out to validate these tools comparing the results with real experiments or other kinds of models. In this line, in the following research [40] conducted by [PERSON] et al., a comparison among zone and field models, about a common atrium building in Hong Kong, was carried out. The four zone models used for this study are: FIRST, CFAST, CCFM.VENTS model developed at the Building and Fire Research Laboratories (NIST, USA) and the NBTC one-room model of FIRECALC developed at CSIRO, Australia. The field model was a self-made fire field model based on computational fluid dynamics theories. While for a quick estimation of probable smoke layer thickness and temperature in a confined fire any of the above mentioned four models can be used, the author highlights the potential of computational fluid dynamics models over zone models to illustrate the simulations. Despite computing time being higher for this kind of simulation, the detailed analysis of the thermal environment was better. Furthermore, in order to validate different CFD models [PERSON] et al., performs a series of experiments [28; 30; 36].