Events

BCAM Workshop Environmental Mathematics Day

Date: Tue, Feb 26 2013

Hour: 09:00

Speakers: Carlos París, Sergio Faría, Leire Ibaibarriaga, Gianni Pagnini, Tomás Chacón

The Hysea Project: a web-based platform for the simulation of geophysical flows

Carlos París Madroñal, Universidad de Málaga, Málaga, Spain

In last years, the EDANYA group of the University of Málaga has been working in the development of the web-based platform HySea allowing the users to run simulations of geophysical flows from their own computers by using a standard browser. The simulations are run in a CPU/GPU cluster located in the Laboratory of Numerical Methods of the University of Málaga.

These simulations are based on the numerical approximation of the systems of Partial Differential Equations that govern the flows to be studied. So far, the models considered are hydrodynamic depth-averaged models whose PDE systems are nonlinear non-conservative and hyperbolic. The approximations of their solutions are obtained by applying high-order finite volume methods.

In the talk, some of the technical difficulties will be briefly discussed and the different applications of the platform (such as river flows, sea currents, floods, avalanches, tsunami waves, etc.) will be presented.

Multiscale Modeling of the Dynamics of Glaciers and Ice Sheets

Sergio H. Faría, Ikerbasque Research Professor, Basque Center for Climate Change (BC3), Bilbao, Spain

Glaciers and ice sheets are essential components of Earth's environmental system, owing to their ability to interact with the atmosphere and the hydrosphere on regional and global scales. These interactions are conspicuous in contemporary environmental issues, including sea-level rise and global warming. They remain also recorded in deep ice, viz. in layers of dust, aerosols and isotopes once deposited on the snow surface and later buried and compacted by the burden of subsequent snowfalls. The resulting stratification makes glaciers and ice sheets unique archives of Earth's climate during the past million years. On the other hand, it also complicates considerably the modeling of natural ice creep, which is the key for understanding the waxing and waning of glaciers and ice sheets over centuries and millennia.

Recent studies have shown that the creep of glaciers and ice sheets is strongly influenced by a complex coupling of intrinsic structures on several scales, ranging from heterogeneous arrangements of dislocations and microscopic inclusions to polycrystalline anisotropy, internal stress networks, and large-scale stratigraphic features, to mention just some. Our knowledge of the genesis and dynamics of most of these structures is still lacking in many aspects, and a holistic perspective of the problem is missing. Furthermore, the multiscale interactions of such structures can hardly be studied in experiments, since they are frequently dependent on strain rates, size- and time-scales that cannot be attained in laboratory. Fortunately, many of these interactions affect locally the mechanical properties of natural ice, leaving temporary imprints on its structure, which can be detected and analyzed with appropriate techniques.

Here we present results of recent investigations of natural ice structures via fieldwork, experiments, and mathematical modeling. The basic strategy is to regard glaciers and ice sheets as complex systems made up of a continuous diversity of constituents via the Theory of Mixtures with Continuous Diversity.

Statistics for fisheries management: anchovy in the Bay of Biscay

Leire IBAIBARRIAGA, AZTI-Tecnalia, Derio, Basque Country, Spain

Regarding fisheries management, the Marine Research Division in AZTI-Tecnalia conducts research for the achievement of sustainable fishing. The work is carried out in collaboration with the fishing sector and the main European research centres. In this talk, I will introduce the scientific work behind the fisheries management in Europe, with special emphasis on the role of statistics. The case study of anchovy in the Bay of Biscay, which is a species of great commercial interest for the Basque fleet, will be presented for illustration. Finally, future research fields will be briefly outlined.

Modelling turbulence effects in wildland fire propagation by the randomized level-set method

Gianni PAGNINI, BCAM-Basque Center for Applied Mathematics, Bilbao, Basque Country, Spain

The level-set is a well-established method for tracking front and it is widely used also for tracking wildland fire propagation. Since the important role of turbulence in fire propagation due to the turbulent nature of the dynamics of the Atmospheric Boundary Layer, as well as the forcing of the fire-atmosphere coupling and the fire-induced flow, a model to include the effects of turbulence on the fireline propagation is discussed. Turbulence randomly transports the hot air mass that can pre-heat and then ignite the area around and ahead the fire. The fire front position gets therefore a random character. The level-set method for tracking the fire line contour is randomized according to the probability density function of the turbulent displacement of the hot air particles. The model emerges to be suitable to simulate a moving fire front displaced by the pre-heating action of the hot air mass itself diffused by the turbulence. This mechanism allows the simulation of the fire overcoming a firebreak zone, a situation that the level-set method can not resolve.

Numerical modelling of shallow hydrodynamic flows by mixed finite elements

Tomás Chacón Rebollo, BCAM-Basque Center for Applied Mathematics, Bilbao, Basque Country, Spain

The hydrostatic approximation is frequently used to derive reduced models of hydrodynamic flows, where the only unknowns are the (3D) horizontal velocity and the (2D) surface pressure. In this talk we shall present the numerical approximation of these reduced models by finite element methods. We shall essentially consider mixed finite element methods, and derive some pairs of stable velocity-surface pressure. We finally present some numerical results that accurately reproduce some physical effects in oceanic flows due to the interaction between surface wind stress and Coriolis forces.