UTFacultiesTNWEventsPhD Defence Giulia Piumini | Fluid Structure Interaction of Turbulent Flows with Complex-Shape Bodies

PhD Defence Giulia Piumini | Fluid Structure Interaction of Turbulent Flows with Complex-Shape Bodies

Fluid Structure Interaction of Turbulent Flows with Complex-Shape Bodies

The PhD defence of Giulia Piumini will take place in the Waaier Building of the University of Twente and can be followed by a live stream.
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Giulia Piumini is a PhD student in the Department Physics of Fluids. Promotors are prof.dr. D. Lohse and prof.dr. R. Verzicco from the Faculty of Science & Technology.

From industrial processes to biological applications, studying the fluid- structure interaction of turbulent flows with complex-shaped bodies is crucial for understanding and optimizing a wide range of natural and engineered systems. This dissertation explores fluid-structure interactions (FSI) across various regimes, utilizing numerical simulations, experimental methods, and data assimilation to investigate phenomena ranging from turbulent multiphase flows to cardiovascular dynamics. Each chapter focuses on a specific problem, offering new insights into understanding and predicting FSI systems. Chapter 1 investigates the behavior of heavy chiral particles in homogeneous isotropic turbulence. These particles inject energy into the turbulence through viscous and pressure forces, amplifying or suppressing turbulence depending on parameters such as turbulence strength, density ratio, and volume fraction. The study shows that chirality introduces rotational effects, coupling translational and angular motions, and generates mean flow vorticity. The ratio 𝑢𝑟𝑚𝑠/𝑣𝑧 quantifies this rotation, which decreases with increasing turbulence strength. Energy spectra reveal significant turbulence suppression at higher volume fractions.

Chapter 2 extends this analysis to light chiral particles. With lower inertia, these particles behave similarly when the density ratio 𝛿 ⟶ 0, showing susceptibility to added mass effects. This leads to altered collision dynamics and the formation of persistent couples, which maintain entanglement longer than heavy particles, reshaping interactions with the flow and influencing turbulence modulation.

Chapter 3 examines the settling behavior of oloid-shaped particles in quiescent fluid. The unique geometry causes complex motions, including tumbling and oscillations, sensitive to initial orientation. The study shows strong agreement between simulations and experiments, although the experimental setup captures only part of the settling process, highlighting the need for better experimental frameworks for more accurate representation.

Chapter 4 develops a computational cardiovascular model based on patient- specific imaging data, using a nudging-based data assimilation approach. This model captures functional parameters such as left ventricular volume and area without requiring electrophysiological models. The chapter addresses challenges in anatomical segmentation and proposes a hybrid strategy to improve simulation fidelity, laying the foundation for incorporating detailed cardiac valve models and expanding to full cardiovascular anatomy.

The dissertation opens several avenues for future research. In chiral particle turbulence, further studies could explore the impact of chirality on small-scale turbulence energetics and extend the analysis to shear-driven systems. For anisotropic particle settling, broader experimental and numerical studies are needed to explore the effects of Reynolds numbers, particle geometries, and initial conditions. In cardiovascular modeling, the incorporation of variational data assimilation or Kalman filters could refine predictions, while expanding anatomical models to include detailed cardiac valve dynamics and using advanced imaging techniques like 4D flow MRI could significantly improve understanding of cardiovascular dynamics.

In conclusion, this work demonstrates the value of integrating numerical, experimental, and data-driven approaches to address complex FSI problems, paving the way for future advancements in engineering and biomedical sciences.