# GoZone: A Numerical Model for Travelling Fires Based on Cellular Automata Concept
## 7 Comparison with BST/FSR 1993: Test 2  
The BST/FSR test series performed in 1993, better known as [PERSON]'s fire tests, consist of nine different compartment fire tests performed in one compartment with varying fuel load, opening size, and ignition methodology [21]. The test compartment was 22.8 m long, 5.6 m wide, and 2.75 m high, with an opening on one short end of the compartment. The fuel was made of wood rib piles uniformly distributed on the whole floor area, ignited at the opposite side with respect to the opening position. The authors consistently observed in the nine tests performed that the fire travelled from the back of the compartment toward the opening, seeking air, then once all the fuel was consumed near the opening region, the fire travelled back again toward the ignition region. This test series is emblematic because it may be regarded as an early example of what is now termed as \"travelling fires\", where the position of the burning zones moved and was severely influenced by the ventilation. Recently, [PERSON] et al. [22] tried to model and represent the \"BST/FSR Test 2\" with FDS [15], obtaining a good agreement with the fire dynamic observed in the test. However, the rate of heat release assigned to each row of rib in the model was extrapolated based on the rib mass loss rate measured during the test and assigned rib by crib according to their position using several ramp functions. The authors thus showed how FDS is able to replicate travelling fire behaviour in under-ventilated condition but were not able to predict its complex behaviour a priori. GoZone was compared with the BST/FSR test 2 in order to evaluate its ability to predict this particular fire dynamic. For test number 2, [PERSON] et al. provided the evolution of the temperature distribution in the compartment for three specific rib lines (Figure 17). These information were used here to extrapolate the fire dynamics and to compare the test results with the model's outputs. The compartment was modelled in GoZone with a mesh size of 1 m and discretised with 205 unstructured quadrilateral cells. Each cell was characterised with the parameters in Table 6.  
The fuel load density is given in Kirby et al. [21]; however, to characterise the fuel cell, GoZone also needs the rate of heat release density and fire growth rate. These input parameters were chosen according to the suggestion provided by Eurocode 1 part 2 where a fuel load density of 380 MJ/m\({}^{2}\) can be associated with a Hotel Room compartment according to Table E.4. (Annex E of EN1991-1-2) Therefore, the rate of heat release density and fire growth rate were chosen consistently according to Table E.5 (Annex E of EN1991-1-2). A comparison with the tests was thus made in a situation that is as close as possible to a design situation in which the fire action is not known a priori. Critical energy of ignition and critical heat flux were not tuned for this particular test but taken as determined in Section 3. Figure 18 shows the results in terms of fire evolution. The fire was ignited on the left hand side and initially propagated slowly toward the opening (Figure 18a), then the increasing temperature in the hot gases and the associated radiation helped the fire to spread faster toward the opening. The compartment at 19 min was completely engulfed in flames. After a few minutes, a transition to an air-controlled situation due to a lack of oxygen took place. Cells on the opposite side of the opening, depicted in yellow (Figure 18b), cannot burn due to a lack of oxygen. The air entering from the opening feeds the burning cells (red) and the fire travels from the opening to the opposite side (Figure 18c). At 64 min, the fire is completely extinguished. Comparison between Figures 17 and 18 show that GoZone can predict the complex fire behaviour observed in this specific test in terms of fire position and total duration.