My research in a few words
I study turbulent flows interacting with complex, time-dependent geometries. This research is located at the frontier of engineering, scientific computing, robotics, numerical modeling and biology. In particular, I study flapping flight of flying insects, including the turbulent flow insects generate and are exposed to, using high performance simulations on large scale supercomputers. The development of wavelet-based tools for simulation, modeling and analysis is an important part of my work. It also includes experimental work on flows (PIV) and living animals. All my work is open source.
A selection of projects I work on
Below you will find a selection of projects that I work on – to give you an idea of what I am interested in and how I work. In general, my mission at the CNRS is interdisciplinary research – at the interface of fluid mechanics, numerical mathematics, high-performance computing and biology.
► Wavelet-based adaptive numerical methods
For some years now, I develop in cooperation with Prof. Kai Schneider (Aix-Marseille Université) and DR CNRS Marie Farge (ENS Paris) a new numerical method for computational aerodynamics of animals. The code is called WABBIT and it is based on biorthogonal wavelets. These wavelets are used to create a dynamically adaptive grid that automatically refines the resolution where necessary to ensure a given precision, and coarsens it where possible. This strategy ensures optimal usage of computational resources. The code is designed for massively parallel supercomputers.
This work is supported by the ANR-DFG Grant “CVSFIT” in cooperation with Prof. Angla Busse (TU Berlin).
► Insects in turbulence
Insect are not like human designed aircraft: they fly in an extremely hostile environment. Predators everywhere, obstacles like plants blocking the way. An on top of that turbulence shaking them every which way. Humans fly for fun, animals fly professionally. How they manage to fly despite violent turbulence – that question fascinates me since a long time.
► Houseflies and wing damage
Insects are role models for roboticians in many ways. They are small (compact design) and much more powerful than our robots in many ways (endurance, efficiency, maneuverability). They have to – animals have to life their lives with what they find in nature. They cannot use seemingly infinite fossil oil to provide abundant energy (and wrecking the planet). Insect wings are the delicate, lightweight structures that make flight possible, and learning about the design principles in nature is essential for designing sustainable new technologies. Insect wings are not repaired – the animal has its wings for its entire lifespan. How they cope with damage to their wings, what the biological cost for this compensation is, and what we can learn from that for robots are some of the questions I wonder about in this project. Specifically, I study (extra)ordinary houseflies, how their wings get damaged over time and how the animals still manage to fly.
This work is done in collaboration with Fritz-Olaf Lehmann (University of Rostock) and Henja-Niniane Wehmann (University of Jena).
► Insects with bristled wings
When Dmitry, Fritz and Alex first approached me with this topic, I thought: that thing never flies. I was wrong. Tiny insects of less than a millimeter – you can almost inhale them – are bizarre lifeforms that each time they fly celebrate a tiny victory over viscosity. Given their size, they are incredibly fast, and many of their adaptions to their tiny kingdoms are breathtaking. The animal on the right is paratuposa placentis, and it is roughly 500µm in size. Its Reynolds number is ~10, a regime that is nonlinear but not turbulent. That makes these simulations shockingly expensive – but we were able to explain why these animals look the way they do, and how and why they are able to fly.
This work is done in cooperation with Dmitry Kolomenskiy (Skoltec Moscow), Alexey Polilov (Moscow State University) and Fritz-Olaf Lehmann (Rostock University)