Development of a Fluid–Structure Coupling Validated with a Confined Fire: Application to Painted Caves

Abstract

In 1994, three speleologists discovered the Chauvet-Pont d'Arc Cave, which contains singular thermal marks on walls deep in the cavity. These alterations arose from intense fires, and understanding their characteristics would help archaeologists suggest hypotheses about the function of such activities. In this context, three confined fires were conducted in a former underground quarry to reproduce thermoalterations similar to those in the Chauvet-Pont d'Arc Cave and extract experimental data. Each fire involved approximately 135 kg of wood, which was continuously supplied by firemen for safety reasons (> 500°C) and burnt in the shape of a tepee 80 cm in diameter for 50 min. This paper presents the validation of a numerical model on this experimentation. The modelling requires coupling between the combustion and wall impact simulations. Thus, a link between the combustion code Fire-FOAM and the thermo-mechanical code Cast3m was created with Python scripts. The results from the simulation agree with the measurements and the observations. More specifically, the analysis is based on the temperatures, gas and particle concentrations, gas velocities, soot deposition, colour changes at the walls and areas likely to spall. These data were collected from thirty-seven measuring points covering the whole quarry. This validated tool will provide information about the features of the fires that occurred within the Chauvet-Pont d'Arc Cave.

Water saturation variation in a fire-heated limestone gallery monitored by ERT

“…Within the quarry, the limestone presents a high variability (Verdet et al 2018, Salmon et al 2020b.…”

“…To acquire the ERT measurements, a micro-ERT profile was also implemented (Figure 1 In order to observe the temperature variations, the instrumentation set-up consists in eight thermocouples, located within the quarry wall and carefully placed at various depths, from 0.5 cm to 4.5 cm (Figure 2 .b and Table 1) and at three different heights along the micro-ERT profile (Figure 2.a) (Verdet et al 2018, Salmon et al 2020b). The micro-ERT profile is located at 1.2 m from the center of the 80-centimeter diameter hearth.…”

“…Notre-Dame of Paris, Deldicque & Rouzaud (2020)) or even natural caves (Carrancho et al 2009, Salmon et al 2019. Fires were ignited in a quarry situated in south-west France , Salmon et al 2020b), aiming at understanding the impact of Paleolithic fires on the Chauvet-Pont-d'Arc Cave walls (Ferrier et al 2017, Salmon et al 2020a.…”

Numerical Reconstruction of Paleolithic Fires in the Chauvet-Pont d’Arc Cave (Ardèche, France)

“…First, the open source code FireFOAM (FireFOAM 2019), which can manage the simulation of fires, was extended. The contributions are briefly itemized here since they have already been detailed (Salmon et al 2019;Salmon et al 2020). A thermal boundary condition, based on energy balance at walls, has been added.…”

“…For the sake of conservation, only numerical tools can reproduce fires in the Chauvet-Pont d'Arc Cave geometry. We thus developed a model to simulate the fires and the induced thermo-alterations on the walls (Salmon et al 2019;Salmon et al 2020). The numerical method is described in the following section.…”