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The Lascaux cave, located in southwest France, is one of the most important prehistoric cave in the world that shows Paleolithic paintings. This study aims to characterize the structure of the weathered epikarst setting located above the cave using Time-Lapse Electrical Resistivity Tomography (ERT) combined with local hydrogeological and climatic environmental data. Twenty ERT profiles were carried out for two years and helped us to record the seasonal and spatial variations of the electrical resistivity of the hydraulic upstream area of the Lascaux cave. The 20 interpreted resistivity models were merged into a single synthetic model using a multidimensional statistical method (Hierarchical Agglomerative Clustering). The individual blocks from the synthetic model associated with a similar resistivity variability were gathered into 7 clusters. We combined the resistivity temporal variations with climatic and hydrogeological data to propose a geo-electrical model that relates to a conceptual geological model. We provide a geological interpretation for each cluster regarding epikarst features. The superficial clusters (no 1 & 2) are linked to effective rainfall and trees, probably a fractured limestone. Another two clusters (no 6 & 7) are linked to detrital formations (sand and clay respectively). The cluster 3 may correspond to a marly limestone that forms a non-permeable horizon. Finally, the electrical behavior of the last two clusters (no 4 & 5) is correlated with the variation of flow rate; they may be a privileged feed zone of the flow in the cave. [ABSTRACT FROM AUTHOR]

Abstract A numerical simulation of a wood fire in a natural gallery is compared with experimental data. Temperatures, velocities, gases and particles concentrations as well as soot deposits are the measured quantities of the experiment. We expose in this article the comparison with a simulation performed by the open-source solver FireFOAM. In order to improve the accuracy of the modeling, the initial numerical tool has been modified. A boundary condition for temperature based on energy conservation has been added to better estimate thermal losses at the walls. A hypothesis regarding vertical velocity in a confined geometry containing a localized fire is also made. By assuming that the velocity is exclusively horizontal, the error between simulation and experiment is reduced. With the aim of comparing the temperature measurements with the simulation accurately, the thermocouple model commonly used in FireFOAM has been changed. The limitations of the previous models are also discussed. Then, two combustion side issues are presented. First, the model of Beresnev-Chernyak computes soot deposit on walls. Second, the fractional effective doses (FED) for toxicity, radiation and heat hazards have been implemented to evaluate the safety of the environment during the fire. Highlights: • A localized wood fire was made within an instrumented confined gallery. • The experimental data are compared with a FireFOAM simulation. • An accurate thermocouple correction added to the tool allows this comparison. • A thermal boundary condition and a hazard modeling are implemented. • Enforcing the velocity to be only horizontal yields consistent results. [ABSTRACT FROM AUTHOR]

Numerous fire marks occur on the walls of the Chauvet-Pont d’Arc cave. Dating indicated that some of the fires were contemporary to the Aurignacian. Violent thermal shocks were observed in surprisingly narrow areas of the cave. This raises numerous archaeological questions about the function of the fires; the answers depend on the location of the hearths, and the intensity of the fires. Numerical simulation was used here to provide information about the behaviour of fires in such confined spaces. An underground non-archaeological site, in a limestone quarry, was equipped to monitor fires in an environment similar to that of the Megaceros gallery of the Chauvet-Pont d’Arc cave. The fire and the movement of heat and smoke in the quarry were simulated by the open source code “Fire Dynamics Simulator (FDS)”. Results were validated on wall temperatures recorded behind and above the fire. The thermo-mechanical impact of the fire on the rock was simulated with CAST3M software, providing the most probable zones for limestone spalling due to thermal gradients. The validated approach will, in a forthcoming study, be applied to the Chauvet-Pont d’Arc cave, in which coupled simulations in the air and in the rock should indicate the location of the hearths and the intensity of the fires that generated the marks. [ABSTRACT FROM AUTHOR]