# A Review of Modelling and Simulation Methods for Flashover Prediction in Confined Space Fires
## 5 Challenges An Opportunities  
Novel techniques used for modelling, simulation and prediction of flashover phenomenon in confined fires have been reviewed in this paper, identifying future opportunities and challenges. As far as modelling and simulation is concerned, the most recent studies of flashover have been reviewed. While the articles analysed describe a deep level of knowledge about this phenomenon, there are some issues that require further exploration. Flashover research reveals some physical events which determine the beginning of this phenomenon, especially upper gas temperature \(\geq\) 600 \({}^{\circ}\)C and heat flux at floor level \(\geq\) 20 kW/m\({}^{2}\). Both factors have to be considered together to define the initial point of this transition phase to fully developed fire. Furthermore, ventilation factor has a vital impact on flashover occurrence. The location and size of the vents in the enclosure maintains a close relation to the development of this kind of phenomenon. Vent identification using computer vision techniques [7] in real time could provide valuable information to predict flashover. Furthermore, flashover is clearly determined by an HRR/time relation, which could be a key issue for prediction with ANN models. The simulations reviewed from mathematical models reveal that nowadays computational fluid dynamics (CFD) simulation predominates over other analysed models. The detailed analysis of thermal environments, which can be used to train and validate ANN with certain accuracy, is one of the many advantages of this type of simulation. Various CFD software packages have been compared in different articles shown in this review. Notice in most cases FDS have been used to conduct research simulations. Not only have been FDS validated with acceptable scores but also ANSYS CFX software obtained similar results. In particular, the use of FDS is widely extended because it is a free and open-source software tool. Furthermore, flashover phenomenon has been widely simulated in most of the articles reviewed. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Authors \& References**} & \multirow{2}{*}{**Flashover**} & \multicolumn{2}{c}{**Research Techniques**} & \multicolumn{2}{c}{**Simulation Software**} & \multirow{2}{*}{**Infrared Sensors**} & \multirow{2}{*}{**TIC**} \\ \cline{3-3} \cline{5-8}  & & **ANN** & & & & & & FDS & ANSYS & **Other** \\ \hline [PERSON], [PERSON], [PERSON] \& [PERSON] et al. [8] & ✗ & ✓ & ✓ & ✗ & ✗ & ✓ & ✗ \\ [PERSON], [PERSON] \& [PERSON] et al. [9] & ✗ & ✓ & ✓ & ✗ & ✗ & ✗ & ✓ & ✗ \\ [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] \& & & & & & & & & \\ [PERSON] et al. [10] & ✓ & ✓ & ✗ & ✗ & ✓ & ✗ & ✗ & ✗ \\ [PERSON], [PERSON], [PERSON] \& [PERSON] et al. [12] & ✓ & ✓ & ✗ & ✗ & ✗ & ✓ & ✗ & ✗ \\ [PERSON], [PERSON], [PERSON] \& [PERSON] et al. [13] & ✓ & ✓ & ✗ & ✗ & ✗ & ✓ & ✗ & ✗ \\ [PERSON], [PERSON], [PERSON], [PERSON] \& [PERSON] et al. [14] & ✗ & ✓ & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ \\ [PERSON], [PERSON], [PERSON] \& [PERSON] et al. [15] & ✗ & ✓ & ✗ & ✗ & ✓ & ✗ & ✗ & ✗ \\ [PERSON] et al. [52] & ✗ & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ & ✗ & ✓ \\ [PERSON] \& [PERSON] et al. [54] & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ & ✗ & ✗ \\ [PERSON] et al. [55] & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ & ✗ & ✗ \\ [PERSON], [PERSON] \& [PERSON] et al. [56] & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ & ✓ & ✓ \\ [PERSON], [PERSON] \& [PERSON] et al. [57] & ✓ & ✓ & ✗ & ✗ & ✗ & ✗ & ✗ & ✗ \\ \hline \hline \end{tabular}
\end{table} 
Table 6: References summary about flashover occurrence prediction show in this section. With regard to TIC, it is important to remark that according to the reviewed articles it is not possible to compare images from FDS simulations with thermal images obtained directly from TIC. Some transformations need to be done before this step, since the final image depends on the technical thermal camera parameters and conditions of the medium (scattering or non-scattering medium).