Research on behaviour of fluids
Raindrops on a car window flow in a different way than drops on soft flower petals. Professor Jacco Snoeijer studies how liquids behave when in contact with a surface and also investigates soft materials. They show surface characteristics and contact behavior very similar to liquids.
“A lot of our work consists of experiments with high-speed cameras,” says Snoeijer. “We film how fluids flow and then try to model what we see. Ideally, we aim to also describe the fluid behavior mathematically, with a formula that can be used in applications where similar flows of fluid in contact with a surface occur.”
The great thing about the physics of fluids, says Snoeijer, is that it deals with fundamental physical phenomena, yet at the same time it is very tangible and can be encountered everywhere in our daily lives. “On YouTube, it was a hit for a while to throw a partially filled water bottle in the air and let it land on its bottom, the water bottle flip challenge. When a group of first-year students wanted to investigate this phenomenon, we took it seriously and wrote a scientific publication together with the students, in which we describe how the water flows inside the bottle and provide a formula for the ideal filling percentage,” he says. “Something similar is the dripping teapot effect. This is a minor practical annoyance in the kitchen, but such phenomena also occur in inkjet printers, for example, where it causes blockages and stains. We are trying to understand what exactly is happening and how you can manipulate fluid flows to prevent drips.”
Supported through an NWO Vici grant, Snoeijer has embarked on a new research direction a few years ago. “We are exploring soft, solid materials, like hydrogels or rubber. These materials are not liquid, but they do behave very similar to liquids under certain circumstances,” he says.
For example, the way they adhere to a surface is very similar to the adhesion of droplets on a hard surface. Snoeijer is looking for universal principles to describe folding, bonding and movement of soft materials. Such knowledge is important for a multitude of applications, from the behavior of gels, to 3D printers and understanding how tissues like our brains fold.
With his work on soft materials, he establishes a connection between his own field of fluid dynamics and that of soft matter. “That is something new, because our scientific fields usually employ different tools and concepts,” says Snoeijer. “With our knowledge of fluid dynamics and surface tension, we can really bring something new to the field of soft matter.”
Education
Every year, Snoeijer encounters the new students of Applied Physics when they are taking their very first steps at university, because he teaches their first course. “Every year it is nice to see how our students come in and how they develop subsequently,” he says. Snoeijer is happy when education and research merge seamlessly. This happens in a coordinated way when he is supervising students working on their graduation project, but sometimes smart questions from students during a lesson also induce scientific progress. Inspired by students, Snoeijer wrote several articles on physics didactics. “A good question encourages you to think even more about how you can explain a certain concept well,” he says. “In some cases, it went one step further and a question or project from students led to new experiments and a scientific publication, as in the case of the water bottle flip.”
About Jacco Snoeijer
Jacco Snoeijer studied Applied Physics in Twente and obtained his PhD at Leiden University. After that he wanted to explore work elsewhere in Europe and completed two postdocs with a Marie Curie Fellowship, in Paris and Bristol. In 2008 he returned to Twente as an assistant professor in the Physics of Fluids group. He received several grants, like an NWO Vidi grant and an ERC grant with which he could build his own research group. As of 2018 Snoeijer professor of Capillary flows and elasticity. In the same year he was awarded an NWO Vici grant for his research into the surface properties of soft materials.
press photos
These press photos can be used, please include the name of the photographer, Fokke Eenhoorn.