Microclimate Simulation for Preservation
Understanding the Deterioration
The decay is part of a complex phenomenon in which the solubilization and crystallization of salts, coupled with microbiological attack, are the most dangerous factors. Contributing to the decaying process are microclimatic variations in temperature, humidity, and airflow.
CISTeC decided to use CFD to simulate these conditions, helping to pinpoint the exact cause of the problem and, hopefully, to suggest a solution. The software was to simulate and predict how changes in wind velocity, airflow, air temperature, surface temperature of the walls, and humidity could help to prevent further decay of the paintings.
The "Room of the Golden Vault" was chosen as the focus for the study, with the expectation of widening the experiment to the entire Domus Aurea if the initial results were positive.
Using previous studies of other historical underground sites, CISTeC was able to define optimal conditions for the conservation of paintings. We used that benchmark against which to measure the internal conditions of the Domus Aurea.
With STAR-CD, CISTeC analyzed microclimate data in the Room of the Golden Vault for the months of January and August, the coldest and hottest periods of the year in Rome. The data were supported by experimental monitoring of environmental parameters such as relative humidity and wind velocity.
The CFD results showed that openings in the masonry were producing turbulent airflow. We believe this was causing the frescoes to decay, but for different reasons in different seasons. In the winter, the optimum temperature for preservation was not being reached. In the summer, the temperature was high enough, but the humidity was too high.
To find a possible solution to the problem, CISTeC ran another simulation in which the model was modified to close the openings in the masonry. The results indicated that such closures would reduce the effects of the airflow within the Golden Room,. We surmised this would help to preserve the frescoes and reduce further deterioration.
The obtained results were in agreement with available experimental data, confirming to CISTeC the accuracy of the CFD analysis. CISTeC now plans to apply the technique to newly discovered and more complex rooms within the Domus Aurea.
STAR-CD's results have provided us with an invaluable tool that will, together with our knowledge of the complex environment that exists underground, help us to prevent the Domus Aurea from further decay. In addition, the noninvasive technique may be helpful in preserving many other sites of architectural and archeological interest.
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Sabatino Albero is with the Interdepartmental Centre of Science and Technology of Historical and Architectural Conservation, University of Rome "La Sapienza," Italy.