Events
Colloquia, thesis defenses, symposia and departmental events at the Department of Mechanical Engineering.
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October 2026
BurgersTour/ME lecture: Floating on Turbulence
From marine litter to ice floes, natural bodies of water are often populated with floating objects spanning vast ranges of size, shape, and concentration. Predicting their behaviour requires understanding how turbulent water motion is altered by the presence of the free surface, and how the underlying turbulence influences the interfacial dynamics between the surface and the floating objects, as well as among interacting floaters. Even in the seemingly simple case where surface waves are negligible, the problem is rich in fascinating phenomena. This seminar presents a series of experiments conducted in flow facilities large and small, in which marginally buoyant particles (millimetric to centimetric, round and irregular, solid and deformable) float on turbulent water. For simplicity, the focus is primarily on two opposite limits. First, a dilute suspension of non-interacting discs significantly larger than the dissipative scales of turbulence is considered. These discs exhibit translational and rotational motions dictated by the local flow, coarse-grained at the scale of the particle. Second, dense suspensions of smaller spherical particles are considered. These form multiscale, percolating clusters bound by capillary forces, whose dynamics is well described by a population-balance framework. Finally, the seminar provides insights into the profoundly different behaviour exhibited by floating rods and oil droplets. Filippo Coletti is Professor of Experimental Fluid Dynamics at ETH Zurich, where he has been since 2020. Previously, he was McKnight Land-Grant Professor of Aerospace Engineering and Mechanics at the University of Minnesota, which he joined in 2014. He completed his doctoral studies at the Von Karman Institute for Fluid Dynamics and the University of Stuttgart, earning his PhD in 2010. He was subsequently a postdoctoral fellow at Stanford University from 2011 to 2013. He received the CAREER Award from the U.S. National Science Foundation in 2015 and an ERC Consolidator Grant from the European Research Council in 2022. He is a Fellow of the American Physical Society and an Associate Editor of the Journal of Fluid Mechanics. He founded and co-organizes the Fluid Mechanics Tour of the Alps, an itinerant seminar series featuring leading researchers in fluid mechanics. His research focuses on multiphase flows, which he investigates using a wide range of experimental techniques, with applications in environmental, biomedical, and industrial systems.
November 2026
Adaptive Differentiating Filter: a solution to the sensitivity trade-off
Abstract: In many control and process monitoring applications, one needs to estimate the derivative of a signal. Standard differentiating filters commonly suffer from the trade-off: reducing the filter bandwidth to improve noise sensitivity also reduces it for the useful signal, leading to smoothed-out high-frequency peaks of the useful signal. In this talk, we present the Adaptive Differentiating Filter (ADF) – a causal real-time filter which solves this trade-off problem. It demonstrates low sensitivity to low-amplitude/high frequency measurement noise, while preserving a wide bandwidth for large-amplitude changes in the process signal. The presentation discusses and demonstrates the filter's favourable performance properties in two practical case-studies: 1) a PID feedback controller for a mechatronic application and 2) monitoring of industrial process signals. It also compares it experimentally with a standard linear low-pass filter-based differentiator and a state-of-the-art robust sliding-mode-based homogeneous differentiator. Bio: Alexey Pavlov obtained his M.Sc. degree (cum laude) in Applied Mathematics from St. Petersburg State University, Russia, and Ph.D. degree in Mechanical Engineering from Eindhoven University of Technology, The Netherlands in 1998 and 2004, respectively. Currently, he holds a full professor position at the Department of Geosciences of the Norwegian University of Science and Technology (NTNU). Prior to that, he held various academic and industrial positions at the Institute for Problems of Mechanical Engineering, Russia (1999), Ford Research Laboratory, USA (2000), Eindhoven University of Technology (2005), NTNU (2005–2009), Equinor Research Centre, Norway (2009–2016). He published the book ’Uniform Output Regulation of Nonlinear Systems: A convergent Dynamics Approach’ with N. van de Wouw and H. Nijmeijer (Birkhauser, 2005). Alexey received the IEEE Control Systems Technology Award (2015) ‘‘For the development and application of variable-gain control techniques for high-performance motion systems’’ (together with M. Heertjes, H. Nijmeijer and N. van de Wouw), and the IFAC World Congress Best Application Paper Award (2011) for the work ‘‘Drilling seeking automatic control solutions”. His inventions within automatic optimization are implemented and used in several offshore fields. His current research interests include control of nonlinear systems, control and optimization of highly uncertain systems, automation and digitalization in the energy industry and various industrial applications of automatic control and optimization.