Karlsruher Institut für Technologie



Karlsruher Vortragsreihe - Forschung und Praxis in Wasserbau und Wasserwirtschaft

Dienstag, 05. Juni 2012, 17:30
KIT, Campus Süd, Theodor-Rehbock-Hörsaal (Hörsaal 59), Altes Bauingenieurgebäude, Otto-Ammann-Platz 1, Geb. 10.81
Two stories about environmental multiphase flows: from bubbles to density currents Vortrag von Dr. Thomas Bonometti, IMFT, Institut de Mécanique des Fluides de Toulouse Bubbles are fascinating objects encountered in many natural and environmental situations. They are present in magmatic chimneys during a volcanic eruption or at the surface of the ocean during wave breaking processes. Knowing the distribution and evolution of the bubbles (of millimeter to centimeter size) in this systems is crucial to better quantify momentum, heat and mass fluxes between the magma/ocean and the atmosphere. In this first part, we present a numerical study of bubble dynamics via an interface-capturing method aimed at computing three-dimensional incompressible two-phase flows involving high density and viscosity ratios, together with capillary effects. We will consider bubbly flows of increasing complexity from the single bubble to several bubbles interacting in a swarm including topological changes such as break-up and coalescence. As a second story, another type of environmental multiphase flows observed at larger scale (from few meter to kilometer) will be considered. Density currents are buoyancy-driven flows which manifest themselves as a current of heavy (resp. light) fluid running below light (resp. above heavy) fluid. While the dynamics of density currents is relatively well understood in the Boussinesq limit, that is for density ratio close to unity, the dynamics of density currents of arbitrary density ratios is less understood. Further understanding is of critical interest for the prevention of hazardous situations such as fires in tunnels, dam break, snow avalanche or accidental release of toxic gases or liquids. In this second part, recent numerical and analytical results will be presented highlighting the influence of some important parameters (Schmidt number, wall friction and initial lock ratio) on the dynamics of high-Reynolds non- Boussinesq density currents.
Institut für Hydromechanik IfH - Institut für Wasser und Gewässerentwicklung IWG, Bereich Wasserwirtschaft und Kulturtechnik
KARLSRUHER VORTRAGSREIHE Forschung und Praxis in Wasserbau und Wasserwirtschaft
Karlsruher Institut für Technologie (KIT)
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76131 Karlsruhe
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