# Experimental and Numerical Evaluation of a Wildland-Urban Interface Fire Scenario
## 2 Materials and Methods  
### Description of the Field Test  
The field fire test was conducted in the central region of Portugal, in Lousa, with the cooperation of the National School for Firefighters (ENB). The experimental test was performed in November 2021. The GPS coordinates of the field are 40\({}^{\circ}\)08\({}^{\prime}\)49.6\({}^{\prime\prime}\) N and 8\({}^{\circ}\)14\({}^{\prime}\)44.6\({}^{\prime\prime}\) W, respectively, and the altitude is 122 m above sea level. The field was previously prepared, and a triangular shape was considered for the test. The test field was approximately 1400 m\({}^{2}\). The length was approximately 70 m, and the width was 40 m (Figure 1a). The average slope is approximately 10%. The fuel break delimiting the test field was the only intervention, creating a path and clear zones to position all the equipment used. A few trees were also in the field, namely 3 _Pinus pinster_ trees located at the top of the test field (Figure 1). The vegetation is characterized by the presence of grass and low-medium height shrubs (0.5 to 1.5 m in height) and the _Pinus pinster_ trees with a maximum height of 9 m. The most common shrub species in the field were _Ulex europaeus_ from the _Fabaceae_ family.  
On the top of the field, a building component was positioned (Figure 1). As previously mentioned, the objective of the test was to gather information concerning the combustion and fire spread and quantify the temperature evolution in the building components mimicking real structures. In this case, sandwich panels with a polyurethane (PUR, with a density of 40 kg/m\({}^{3}\)) core were used. This type of construction product is widely used as cladding in industrial buildings. The external metallic layers of the sandwich panels were fabricated in S250 GD+Z steel, according to EN 10346 [43], with a thickness of 0.5 mm. The height of the panels was 2.5 m, and the width was 1.0 m. The thickness of the vertical panels was 200 mm, whereas the thickness of the top horizontal panel was 80 mm. The reaction to fire classification of PUR according to EN 13501-1 [44] is B-s2, d0.  
The physical obstruction, comprising a set of sandwich panels, was instrumented with 15 disk type-K (TMS Europe, Hope Valley, UK; chrome-alumel wires, Cr-Al) thermocouples at different locations, as depicted in Figure 2, to monitor, during the entire test, the temperature evolution in the surface of the panel when exposed to a wildfire. The distances between shrubs and the building component and between the tree (Tree 3) and the building  
Figure 1: Overview of the field: (**a**) main dimensions, (**b**) positioning of the obstruction, IR camera, and ignition line.  
component were 0.5 and 5 m, respectively. The fire test was also monitored using drones, stationary cameras, and IR cameras (FLIR A600, through FLIR representative MRA, Grupo ALAVA, Lisbon, Portugal), positioned approximately 25 m from the building component. The field was ignited from the bottom part of the field, hence reproducing an upslope fire scenario. The ignition was performed using a drip torch.  
The weather conditions were assessed and monitored before the test for that specific location. Additional data was also provided by IPMA (Instituto Portugues do Mar e da Atmosfera, Lisbon, Portugal). The average weather conditions were as follows: ambient temperature of 20.6 \({}^{\circ}\)C, relative humidity of 43%, and a wind velocity of 1.5 m/s in the northeast (NE) direction. It is worth mentioning that one of the most important objectives of this test was to collect data to feed the advanced full-physics CFD models under development. In the following section, the full-physics model developed to reproduce this experimental test is described.