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Universität Augsburg
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Universität Augsburg
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Professor Dr. Yuval Dagan
Technische Universität München & Universität Augsburg
spricht am
Dienstag, 12. Januar 2027
um
16:00 Uhr
im
Raum 2004 (L1)
über das Thema:
| Abstract: |
| Interactions between shear flows and submicron particle dynamics play an important role in natural and engineering applications, including medical flows, atmospheric flows, energy systems, and envi-ronmental applications. Turbulent particle-laden flows may involve multiphase phenomena, chemical kinetics, and multiple scales. Submicron particles such as atmospheric aerosols and soot may sig-nificantly alter transport, aggregation, and cloud microphysics based on local flow structures and inter-particle forces. However, the exact mechanisms of particle transport, growth, and reaction in shear flows remain elusive. The dispersed phase significantly complicates the mathematical for-mulation and computation of multiphase flows due to complex interphase and particle interactions. Although computational methods have improved significantly over the years, most existing models rely on simple analytical laws and empirical correlations and heavily assume classical Brownian mo-tion. Moreover, shear-driven transport and anomalous diffusion are rarely accounted for in either high-fidelity simulations or traditional models. In this talk, a generalized computational framework for interacting submicron particles will be presented. This framework synthesizes a fully Eulerian approach that combines a low-dissipation carrier-flow numerical scheme with a quadrature moment method. Using this approach, particle in-teractions, including contact forces, electrostatic interactions, agglomeration, breakup, and chemical reactions, can be realized. Complementary analytical solutions of Brownian motion in shear flows form the foundation for advanced closure models for submicron-sized particles. By solving the Langevin equations using stochastic calculus, we resolve particle mean-squared displacement at all timescales for two-dimensional parallel shear flows described by polynomial velocity profiles, capturing tran-sient regimes and shear-induced anomalous diffusion. We also demonstrate how transverse external body forces, such as gravity, alter transient diffusion and settling dynamics across regions of vary-ing velocity gradients. Finally, we demonstrate how coupling between particulate matter and fluid transport drastically changes the carrier-fluid statistics, including turbulence modulation, drag, and preferential clustering. These findings may apply to a vast number of fluid mechanics applications in-volving particle-laden flows, such as atmospheric aerosol transport, climate radiative forcing, wildfires, combustion stability, and aerospace propulsion. |
| Hierzu ergeht herzliche Einladung. |
| Prof. Dr. Michael Schlottke-Lakemper |
Kaffee, Tee und Gebäck eine halbe Stunde vor Vortragsbeginn im Raum 2006 (L1).