Per Lötstedt – författare

Multiscale problems naturally pose severe challenges for computational science and engineering. The smaller scales must be well resolved over the range of the larger scales. Challenging multiscale problems are very common and are found in e.g. materials science, fluid mechanics, electrical and mechanical engineering. Homogenization, subgrid modelling, heterogeneous multiscale methods, multigrid, multipole, and adaptive algorithms are examples of methods to tackle these problems. This volume is an overview of current mathematical and computational methods for problems with multiple scales with applications in chemistry, physics and engineering.

Most problems in science involve many scales in time and space. An example is turbulent ?ow where the important large scale quantities of lift and drag of a wing depend on the behavior of the small vortices in the boundarylayer. Another example is chemical reactions with concentrations of the species varying over seconds and hours while the time scale of the oscillations of the chemical bonds is of the order of femtoseconds. A third example from structural mechanics is the stress and strain in a solid beam which is well described by macroscopic equations but at the tip of a crack modeling details on a microscale are needed. A common dif?culty with the simulation of these problems and many others in physics, chemistry and biology is that an attempt to represent all scales will lead to an enormous computational problem with unacceptably long computation times and large memory requirements. On the other hand, if the discretization at a coarse level ignoresthe?nescale informationthenthesolutionwillnotbephysicallymeaningful. The in?uence of the ?ne scales must be incorporated into the model. This volume is the result of a Summer School on Multiscale Modeling and S- ulation in Science held at Boso ¤n, Lidingo ¤ outside Stockholm, Sweden, in June 2007. Sixty PhD students from applied mathematics, the sciences and engineering parti- pated in the summer school.

The European Conference on Numerical Mathematics and Advanced Applications (ENUMATH) was held from June 29-July 3, 2010, in Uppsala, Sweden. This was the eighth conference in a series of biannual meetings starting in Paris (1995). S- sequent conferences were organized in Heidelberg (1997), Jyvas .. kyla .. (1999), Ischia (2001), Prague (2003), Santiago de Compostela (2005), and Graz (2007). ENU- MATH 2009 attracted over 330 attendees to the scienti c programme, with ten invited speakers, one public lecture, 32 minisymposia, and more than 280 presen- tions. This volume contains a selection of papers by the invited speakers and from the minisymposia and the contributed sessions. The purpose of the conference was to create a forum for discussion and d- semination of recent results in numerical mathematics and new applications of computational methods. Many subjects were covered in the talks and a few of the topicsrepresentedin these proceedingswere discontinuousGalerkinmethods, nite elementmethodsindifferentapplications,methodsfor uid ow,electromagnetism, nancial engineering,structuralmechanics, optimalcontrol, andbiomechanics.The minisymposia listed below with their organizers also give an impression of how broad the scope of the conference was: Adaptivity for non-linearand non-smooth problems, part I & II, Ralf Kornhuber, Andreas Veeser Advanced techniques in radial basis function approximation for PDEs,partI & II, Natasha Flyer, Elisabeth Larsson Advances in numerical methods for non-Newtonian ?ows, part I & II, Erik Burman, Maxim Olshanskii, Stefan Turek Anisotropicadaptivemeshes:erroranalysisandapplications,partI&II,Thierry Coupez, Simona Perotto Asymptotic linear algebra, numerical methods, and applications, part I & II, Marco Donatelli, Stefano Serra-Capizzano Biomechanics, part I & II, Gerhard A.