Preserving the Domus Aurea with CFD

August 14, 2003

The Domus Aurea was built in Rome by Emperor Nero in 64 AD. Known as The Golden House, the Domus Aurea was richly decorated with frescoes and precious stuccoes and covered in pure gold, representing imperial Roman architecture at its finest. Following Nero’s fall in 68 AD, the Domus Aurea was completely buried under Emperor Trajan’s baths. The Golden House remained underground for centuries and has only been partially opened to visitors since 1999.

Throughout Rome’s colorful history, The Domus Aurea has survived as one of the world’s most architecturally complex hypogean (underground) structures. However, after one thousand nine hundred and thirty nine years, the elements have taken their toll on this national treasure. Adversely affected by the microclimatic conditions inside the Golden House, the rich frescoes have started to decay.

Now, Italy’s Interdepartmental Centre of Science and Technology for Historical and Architectural Conservation (CISTeC) is using computational fluid dynamics software from CD-adapco to help rescue the Golden House from the elements and avoid the risk of losing this national treasure forever.

Dr Sabatino Albero of CISTeC explains the extent of the problem: “The Domus Aurea is due to be fully re-opened to the public, so it was vital that we found a solution to the problem of the decay before the deterioration became more serious.

“ The Decay is part of a complex phenomena in which the solubilization and crystallization of salts, coupled with microbiological attack, are the most dangerous factors. However, internal microclimatic conditions within the Domus Aurea, such as temperature, humidity and airflow, are also playing a significant part in the decaying process.”

CISTec decided to use computational fluid dynamics (CFD) to simulate the conditions inside the Domus Aurea, helping them to pinpoint the exact cause of the problem and hopefully how to solve it. STAR-CD, the leading CFD software tool from CD-adapco, was chosen to carry out the investigation. The software was to simulate and predict how changes to factors such as wind velocity, airflow, air temperature, contact temperature of the walls and humidity could help to prevent further decay of the paintings.

Explaining the choice of software over the limitations of more traditional recording techniques, Dr Albero said: “Usually, we measure the condition of the masonry using a limited number of probes. CFD simulation offered us the opportunity to carry out a completely non-evasive study. From our contacts with the University La Sapienza in Rome, we already knew about STAR-CD’s capabilities and versatility, particularly in the simulation of energy and mass flow, so it seemed the obvious choice.”

The Room of the Golden Vault was chosen as the focus for the study, with a view to widening the experiment to the entire Domus Aurea if the initial results were positive.

Using previous studies of other historical underground sites, such as the Hebrew Catacombs at Torlonia in Rome, CISTeC was able to define the optimal conditions for the conservation of paintings. This could then be used as the benchmark against which the internal conditions of the Domus Aurea would be measured.

Using STAR-CD, CISTeC analyzed microclimatic data in The Room with the Golden Vault for the months of January and August, the coldest and hottest periods of the year in Rome. The data was supported by experimental monitoring of environmental parameters such as the relative humidity of the air and wind velocity.

The CFD results showed that openings in the masonry were producing turbulent airflow, causing the frescoes to decay. This decay was happening in both seasons, but for different reasons: in the winter the optimum temperatures for preservation were not being reached and in the summer, the temperatures were warm enough but the humidity was too high.

To find a possible solution to the problem, CISTeC ran a modified CFD simulation in which the openings in the masonry were closed. The results of this proved that reducing the effects of the airflow within the Golden Room would indeed 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 provide us with an invaluable tool that, together with our knowledge of the complex environment that exists underground, will help us to prevent The Domus Aurea from further decay”, concludes Dr Albero. Naturally, it is not just the Domus Aurea that will benefit from this new approach. The non-evasive technique will help us to preserve many other sites of architectural interest for future generations to enjoy.” “