# Computational Fluid Dynamics of Compartent Fires: A Review of Methods and Applications
## 4 Discussion and Conclusions  
Reviewing available sub-models and CFD methods for numerical simulations of compartment fires provides an appropriate framework and procedure for future studies. However, to the best of authors' knowledge, there is no exact algorithm for choosing the best sub-models in the case of a compartment fire and it totally depends on the specific situation, available computing resources, required accuracy and precision, purpose of study, etc. CFD and its applications in fire simulation are complicated operations and need a high level of expertise to implement effectively. This study provides an overview of available CFD methods for simulating different stages of fire, with a particular focus on fires occurring in enclosed spaces. It serves as a fundamental resource for CFD users interested in compartment fire modeling, helping them identify the most appropriate sub-models and tools for their specific needs. Focusing on CFD modeling aspects such as computational mesh and boundary conditions, as well as physical features including turbulence, pyrolysis, combustion, radiative heat transfer, and extinction, different available sub-models in CFD modeling of the compartment fire have been presented. Moreover, by reviewing relevant conducted studies, their reliability and applications have been investigated. The advantages or disadvantages of different methods have been presented in the current study. Nowadays, one of the main reasons for CFD modeling is to reduce the number of experimental tests due to their cost and corresponding risks. Meanwhile, the necessity of reliable test results to achieve more physical details and material properties, as well as the requisiteness of calibration tools for CFD models, pushes researchers to conduct experimental tests parallel to numerical simulation. It should be noted that predictive simulations of compartment fires needs more attention as they still have limits, especially in cases when either there is no available experimental measurement, or they are not able to cover all the simulation aspects, e.g., when fire development needs to be modeled in the blind or semi-blind modes, as they were shown to be incapable of replicating initial and extinction stages in compartment fire. In addition, more experimental tests for obtaining the thermochemical properties of materials such as fuels can enhance CFD accuracy when it comes to predictive (i.e., semi-blind or blind) simulation. In other words, conducting more precise tests on fuel combustion will provide more details about their behavior and decomposition which is helpful in combustion modeling and pyrolysis; an example being initial inputs for yield of CO, CO\({}_{2}\), and soot, or radiative fraction of the fuels in CFD tools such as FDS in under-ventilated conditions which differs from well-ventilated conditions. Although there are some reference values available for standard conditions such as well-ventilated, modelers should rely on their own knowledge and trial/error methods to achieve credible simulation in other conditions like under-ventilated compartment fires. Regarding the importance of radiative heat transfer modeling, it should be noted that a compartment fire typically possess both regions: optically thin in areas with low concentrations of radiative species (such as soot or combustion gases like CO\({}_{2}\) and H\({}_{2}\)O) or in areas where the path length is short like near the openings, and optically thick close to the flames or in smoky areas, where soot and other product species are dense. Therefore, choosing a proper method to solve the RTE and predicting the absorption coefficient may be challenging. In many cases, the model choice involves compromises that may limit the precision of radiation predictions, particularly for flame extinction, where small errors in radiative heat transfer can have significant effects.