סמינר מחלקתי מאת איוון ליטוינוב
Experimental fluid mechanics: from unsteady vortex dynamics to MEMS-based flow sensing
Abstract:
Experimental fluid mechanics, relying on both intrusive and non-intrusive methods, continues to play a pivotal role in advancing our understanding of unsteady turbulent flows. In this talk, two examples of research projects in this field will be given.
In the first part, the spiral vortex breakdown phenomenon (precessing vortex core), which emerges as a result of global instability, will be discussed. This research is motivated by applications in hydraulic turbines. Experimental results obtained in a scaled-down aerodynamic test rig, together with data-driven methods for predicting spiral vortex breakdown, will be presented.
The second part focuses on the development of a novel flow sensing concept, establishing an alternative class of flow measurements that combines mechanical and thermal principles within a single MEMS (micro-electromechanical systems) device. The sensing element is based on an initially curved, bistable single-crystal silicon microbeam, enabling a significant reduction in over-temperature while simultaneously improving velocity sensitivity and expanding the sensor’s dynamic velocity range. The feasibility of the sensor is validated through multiple laboratory and wind tunnel experiments, including measurements of velocity and shear stress, as well as the detection of flow separation. The figure shows the experimental detection of the reattachment point in the boundary layer flow over a rib. Finally, the developed sensor is tested in a real-world environment through installation on a commercial UAV.
Figure: (a) Experimental setup for detection of the reattachment point in the boundary layer flow over a rib and (b) wall shear stress measured using the MEMS sensor.
Bio:
Dr. Litvinov holds a B.Sc. and M.Sc. (2010, 2012) in Physics from Novosibirsk State University and Ph.D. (2016) from the Kutateladze Institute of Thermophysics. Following short-term postdoctoral fellowships at the DLR Institute of Combustion Technology and the Technical University of Berlin, he led research on unsteady swirl flows at the Kutateladze Institute of Thermophysics. In 2023, he joined Tel Aviv University, where he is currently a Senior Research Associate in the School of Mechanical Engineering. His position is supported by the first competitive VATAT program (2023–2028), which establishes tracks for non-faculty researchers.
LinkedIn: https://www.linkedin.com/in/ivan-litvinov88/
Google Scholar: https://scholar.google.com/citations?user=lPQgN0AAAAAJ&hl=en
