Tidlegare gjesteforelesninger og seminarer - Side 87
Fredagskollokvium
The slow growth of a crack in windshield represents a mechano-chemical process: The stress at the tip of the fracture is not high enough to cause rapid fracture motion. Instead, fracture motion is determined by the diffusion of hydrogen to the crack tip, where it weakens the material, leading to crack tip propagation. The velocity of the fracture depends on the coupling between deformation, transport, and reactions. Similar coupled processes determine the rate of many reaction processes of geological relevance, such as weathering and carbonation during mineralogical CO2 sequestration. We have developed numerical model that allow us to address mechano-chemical processes during fluid infiltration. The model demonstrates that fracturing assisted reaction fronts in shrinking materials propagate with a constant velocity and width, and that the reaction rate in volume increasing reactions may be accelerated by feedback processes between fluid flow, mechanical deformation, and reactions.
Anders Malthe-Sørenssen is professor at the Department of Physics, working at the center for Physics of Geological Processes
Friday seminar by Anna Qvarnström.
Fredagskollokvium
Jan Erik H. Weber, Department of Geosciences, University of Oslo Göran Broström, Norwegian Meteorological Institute, Oslo Nonlinear density-driven convection in a conditionally unstable fluid is studied theoretically. The novelty here is that the destabilizing basic density gradient is expressed in terms of the vertical perturbation velocity through a unit step function. This is done by introducing a one-way source step function due to phase transitions in the equation for the perturbation density. Then we can model the fact that the density-gradient is unstable when the perturbation vertical velocity is upward (positive), and stable when the vertical perturbation velocity is downward (negative), characterizing conditional stability. Linear analytical solutions as well as numerical results for nonlinear two-dimensional steady convection are presented.
Jan Erik Weber is professor at Department of Geosciences
Fredagskollokvium
Friday seminar by Stephen H. Schneider and Terry L. Root
Friday seminar by Jon Fjeldså.
Friday seminar by Bernard Cazelles.
Fredagskollokvium
Extra CEES/MERG seminar by Hanna Johannesson.
Friday seminar by Homayoun C. Bagheri
Friday seminar by Erik Svensson
Fredagskollokvium
Extra CEES Seminar by Melanie Stiffel
Friday seminar by Stefan van Dongen
Fredagskollokvium
Fredagskollokvium
Fredagskollokvium
Fredagskollokvium (OBS! Klokkeslett endret)
Friday seminar by Augustine Arukwe
Fredagskollokvium