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Ivan Lunati

The calculator

Apr 13, 2022 | NORBERT RAABE

While setting up his new lab at Empa, the Covid pandemic made Ivan Lunati's work quite a bit harder – and at the same time provided exciting questions for his research. In the future, Lunati will, together with his team, continue to address a wide range of topics – as a passionate theorist with a soft spot for practical applications.

Ivan Lunati in front of a blackboard with formulas for the spread of covid pathogens. The water vapor in front of him helps with laboratory experiments on indoor aerosols. Image: Empa

The two worlds, in which Ivan Lunati feels at home, can be seen on his office wall immediately to the left of the entry: photos of him hurtling downhill through the deep powder near Verbier. And right next to it, a whiteboard with notes, sketches, integrals, differentials ... – a "wall of ideas" because creative research work is easier for him when he's on the move.

The physicist, who heads one of Empa's scientific labs since February 2020, has enough tricky tasks. For example, the questions of where and how corona viruses spread – whether in cable cars and classrooms or throughout Switzerland and Germany. The results of this research triggered a massive response – and many media appearances with fellow researcher Hossein Gorji from his team. A topic that certainly facilitated the start of the new lab.

Ivan Lunati

Career: Postdoctoral studies at ETH Zurich, Institute of Fluid Dynamics, Senior Scientist at ETH Lausanne, SNSF Professorship at the University of Lausanne, Institute of Earth Sciences. Since February 2020 Empa Head of Department.

Science: Physics studies at the University of Milan, PhD at ETH Zurich, research on porous media, fluid dynamics, multiscale modeling, data science and other fields with numerous publications. Member of numerous expert committees and panelist for funding agencies.

The pandemic as a source of ideas

But why Covid scenarios, of all things, which so many researchers have been jumping on since the beginning of the pandemic? Out of curiosity! Lunati studied the scientific literature on the spread of aerosols along with viruses and found quite a few open questions. "My life was so affected by masks and hygiene and distance rules," he said, "I wanted to understand why my world was suddenly upside down." And everyday work even more difficult: Home office and other measures certainly didn't make establishing the lab any easier, Lunati adds.

In the meantime, his team has taken shape: three senior researchers plus postdocs, students and experienced technicians are already staffing the lab, which also includes a water and a wind tunnel – large-scale infrastructure for experiments that can be used to explore complex flow phenomena.

For example, for Covid research. To better understand how droplets containing pathogens move and spread in the air, the team developed a "cough machine." As if from lungs, two piston tubes exhale compressed air from a "mouth" with relative humidity, temperature, and droplets as if from a human. Two cameras in the wind tunnel record how the droplets move about. Using tiny particles to visualize air movements, more accurate models can be developed of how viruses spread in real life.

This is uncharted territory for Lunati and his team, who have all the more experience in other areas. His long-standing research interest is porous media. And the question: How can we describe mathematically which substances move how in those media? A picture on the lab's homepage illustrates how tricky this is: What appears to be a tangle of colored worm tubes shows the shape of air penetrating a sandstone with tiny pores, the physicist explains with a point of his finger – displacing water that was there before.

Complex insights with practical value: Years ago, Lunati was already helping to make such knowledge useful for groundwater, radioactive waste storage, petroleum deposits or environmental problems. "Companies invest a lot in numerical methods," says the physicist, "you have to be able to describe how water, oil or gas moves in the underground reservoirs – from the smallest pore in the rock to the scale of kilometers." Such insights could also help in future climate protection efforts to safely store atmospheric CO2 underground.

For the past 20 years or so, the physicist has been working on multiscale modeling, as this field is called, which research groups around the world are working on: simulations from the smallest to the largest – for example, from the quantum scale to atomic and molecular bonds to structures visible to the naked eye. Such models could also be useful for new materials. Take aerogels, for example: In future, these extremely porous materials will be used to filter CO2 molecules from the atmosphere. When it comes to the question of how an aerogel has to be manipulated in detail for this purpose, Lunati's team cooperates with scientists in other Empa labs.

Communicate and connect
In the wind tunnel with Claudio Mucignat (left) and Hossein Gorji. Image: Empa

Porous media as a beacon of hope? Seemingly hard to convey to laypeople, but Lunati once brought it closer to children – at an open lab day at the University of Lausanne. Using the example of drinking water production, he recounts with a mischievous smile, "I played with sand, water and porous material, from a 3D printer. Simply to stimulate the children to engage with research."

Making complex things intelligible gives him palpable pleasure – and is by no means a contradiction to how he sees himself. "I'm a theoretical person," Lunati says, "theory is important to me." But that doesn't mean he neglects a practical view – on the contrary: "If I work on devising new models, they can later on be used by other people – in a wider variety of fields."

That's his vision for other topics as well. Take embodied machine learning, for example: Drones, which Empa experts are developing, could be equipped with sensors and novel algorithms to become intelligent by learning while interacting with their environment to collect data. Take the spread of corona viruses, for example: Instead of conventional computational models that simulate viral spread based on different populations, future models could even link single individuals.

Lunati reaches for a printout on the office desk: beneath a map of Switzerland, a circular network of countless black spots connected by pale strokes. "These dots could describe people and all the lines their contacts," he explains. Such a network does not emerge from classical statistics, but from intelligent data. Such methods could also reveal unknown interactions and could be used to refine conventional models.
Intuition as a researcher's virtue
Empa researchers Hossein Gorji and Ivan Lunati developed scenarios for Covid spread. Image: Empa

When Lunati talks about science, you can feel his enthusiasm for ideas ... – the whiteboard in his office will hardly ever be blank. Just like the classic blackboard in the bright hall his team uses for meetings and discussions, littered with mathematical formulas. Eventually, Lunati also wants to impart a way of thinking, a mindset: a certain intuition to simplify and not drown in masses of data – not just finding some formula, but a simple and, yes, also a beautiful solution to the problem at hand.

"In that sense, I'm an old-fashioned scientist," he admits, "I want to describe the world." Reduce the complexity – for solutions and ideas that can then be applied to a variety of questions. That's how he would like his lab to be: diverse, yet at the same time focused so that its research can be summed up in one sentence. And yes: His team should still grow. "On a hundred-meter sprint, we'd be at 50 meters now," he says, "but it's a marathon, really."

Further information
Dr. Ivan Lunati
Laboratory for Multiscale Studies in Building Physics
Phone: +41 58 765 4111

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