Study on critical length for simulation in tunnel fires

Reasonable simulation length is of great significance to improve the computational efficiency. However, few research about the critical length for simulation have been conducted. In this study, critical length for simulation in tunnel fires was investigated numerically and theoretically. Through analyzing the variation of smoke layer temperature and smoke mass flow rate under different tunnel length, a criterion for selecting critical length is presented. Effect of tunnel cross-section and heat release rate on the critical length for simulation will be clarified. The linear growth relationship between the nondimensionless critical length L* and nondimensionless heat release rate Q* was obtained. This model perform good agreement with the full-scale tunnel fire test values of predecessors.