Page 37 - COMSOL_News_2016
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FIGURE 5. To understand the moisture transport, which can cause damage like that pictured above (left), van Schijndel created a COMSOL model that
accurately couples heat and moisture transport through a wall (right).

the room and the building façades, and also accounted for             “Historic structures are facing unprecedented threats to
the cooling effects of outdoor shade.                              their integrity from climate change, increased urbanization,
                                                                   and other factors. At the same time, the regulations
   The results predicted the temperature on each wall at           governing their preservation have never been stricter, because
different times of day, indicating the best locations for          it is a societal bene t to preserve the legacy of the past. The
protecting sensitive objects from sunlight and heat damage.        ability to use sophisticated modeling and simulation tools such
“It is extremely important to know such precise temperature        as COMSOL is an important part of the toolkit that helps us
distributions so that, for example, paintings can be hung in
locations where they will be less affected by solar heating,”      meet those requirements,” said van Schijndel. v
van Schijndel said.
                                                                   FIGURE 6. Both images show COMSOL simulations of a cross section
   Moisture damage is another major issue that can damage          of a wall on which a painting is hanging. The left image shows the
walls, buildings, roofs, and the contents of a room. Because       temperature distribution in the wall and painting at a given point in
in older structures it isn’t always clear where the moisture       time, while the image on the right shows the rate of change of relative
enters a building or room, van Schijndel sometimes uses            humidity in the wall and the painting at that same point in time. This
COMSOL Multiphysics as an investigative tool.                      model can help predict stress and strain, which impacts historic buildings
                                                                   and artifacts, giving experts the information needed to take appropriate
   “The idea is to deduce how moisture might be entering by        damage mitigation actions.
running multiphysics simulations that include measurements
of relative humidity at many different locations. Areas of                                                                      From left to right: Henk
high relative humidity give clues as to how the mass transport                                                                  Schellen, Zara Huijbregts,
of moisture occurs, and we couple this information with                                                                         and Jos van Schijndel.
heat transfer simulations because heat drives the moisture
distribution,” he said.

   Van Schijndel developed a COMSOL model of moisture
transport in a wall with visible leakage damages near the
window. His model enabled him to deduce where the
moisture was coming from (see Figure 5). He and his students
used this technique to model thermal bridges using different
materials, analyze how the positioning of insulation in uences
heat transfer from the inside to the outside of a building,
and to understand how moisture travels through different
building materials such as concrete, stone, and insulation
(see Figure 5).

   Given that temperature and humidity are major drivers of
stress and strain on precious objects such as historic paintings,
the ability to accurately couple these together in a model can
lead to better predictions of potential damage. Van Schijndel’s
model calculates the temperature distribution throughout the
wall and painting, as well as the relative changes in humidity
(see Figure 6).

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