Workshop on Wave Propagation and Scattering, Inverse Problems, and Applications in Energy and the Environment November 21-25, 2011 as part of the Radon Special Semester 2011 on Multiscale Simulation & Analysis in Energy and the Environment The efficient computation of wave propagation and scattering is a core problem in numerical mathematics, which is currently of great research interest and is central to many applications in energy and the envi- ronment. Two generic applications which resonate strongly with the central aims of this special semester are forward wave propagation in heterogeneous media and seismic inversion for subsurface imaging. As an example of the first application, modelling of absorption and scattering of radiation by clouds, aerosol and precipitation is used as a tool for interpretation of (e.g.) solar, infrared and radar measurements, and as a component in larger weather/climate prediction models in numerical weather forecasting. One key numerical component in this modelling is the prediction of the total optical properties and the full scattering matrix from an ensemble of irregular particles. The underlying mathematical problem is that of accurately computing high frequency wave propagation in a highly heterogeneous medium. As an example of the second application, inverse problems in wave propagation in heterogeneous media arise in the problem of imaging the subsurface below land or marine deposits. Solutions to this problem have a number of environmental uses, for example in the location of hydrocarbon-bearing rocks, in the mon- itoring of pollution in groundwater or in earthquake modelling. A seismic source is directed into the ground and the material properties of the subsurface are inferred by analysing the observed scattered field, recorded by sensors. The inversion process (a large scale optimisation problem) is complicated by the presence of multiple reflections and the fact that the scales involved in the exploration of sub-marine, sub-basalt or sub-salt oil reservoirs can be many kilometres in extent, leading to a challenging multi-scale problem. Current iterative methods for solving the inverse problem involve repeated solution of the for- ward problem (the computational kernel), which is typically a frequency-domain reduction of the elastic (or scalar) wave equation with high frequency and typically highly spatially varying wave speed. If the inversion is to be competitive, the key underlying problem to be overcome is the design of robust and scalable solvers for the large highly indefinite linear systems arising from these problems. The workshop will bring together key numerical mathematicians whose interest is in the analysis and computation of wave propagation and scattering problems, and in inverse problems, together with prac- titioners from engineering and industry whose interest is in the applications of these core problems. Particular problems to be considered will be (i) The design of accurate methods for solving frequency domain problems; (ii) The use of wave enriched and other hybrid approximation strategies in the solution of high-frequency problems; (iii) Fast linear algebra solvers for frequency domain problems in heteroge- neous media; (iv) advanced inverse problem approaches for wave problems such as reverse time migration which move away from traditional ray-based approaches in the high frequency case. Workshop Organizers Ivan G. Graham, University of Bath, UK Ulrich Langer, Johann Radon Institute & University of Linz, Austria Jens Markus Melenk, Vienna University of Technology, Austria Mourad Sini, Johann Radon Institute, Austria cover picture of tsunami simulation in Indian Ocean: courtesy of J¨ornBehrens (KlimaCampus, Universit¨atHamburg) and Widodo S. Pranovo (Indonesia). Welcome to Linz and thank you very much for participating in the sixth RICAM Special Semester on Multi- scale Simulation & Analysis in Energy and the Environment, hosted by the Johann Radon Insitute for Computational and Applied Mathematics (RICAM) from October 3 to December 16, 2011. Technological advances have greatly improved our quality of life. However, they bring with them a huge surge in energy requirements which in turn puts at risk our entire bio-sphere. It is of paramount importance to predict these risks and to develop better solutions for the future. One of the central tasks is the accurate simulation of multiphase flow above and under ground. The risk analysis and uncertainty quantification, as well as the assimilation of data require statistical tools and efficient solvers for stochastic and deterministic PDEs as well as for the associated inverse problems. The key features that make it extremely hard to predict these physical phenomena accurately are the multiple time and length scales that arise, as well as the lack of and uncertainty in data. Because of the highly varying scales involved, the resolution of all scales is currently impossible even on the largest supercomputers. While there is a fairly long history of empirically successful robust computational techniques for certain multiscale problems, the rigorous (numerical) analysis of such methods is of extremely high current interest. The goal of the special semester is to provide a stimulating environment for civil engineers, hydrologists, meteorologists and other environmental scientists to address together with mathematicians working at the cutting edge of rigorous numerical analysis for multiscale (direct and inverse) problems the emerging challenges in the quantitative assessment of the risks and uncertainties of atmospheric and subsurface flow, focusing in particular on • Simulation of Flow in Porous Media and Applications in Waste Management and CO2 Sequestration • Large-Scale Inverse Problems and Applications in the Earth Sciences • Data Assimilation and Multiscale Simulation in Atmospheric Flow • Wave Propagation and Scattering, Direct and Inverse Problems and Applications in Energy and the Environment • Multiscale Numerical Methods and their Analysis and Applications in Energy and the Environment • Stochastic Modelling of Uncertainty and Numerical Methods for Stochastic PDEs Specific activities planned for the Special Semester are • 4 thematic workshops addressing some of the key topics of the Special Semester; • Special Lecture Series on "Multilevel Methods for Multiscale Problems"; • Graduate Seminar on "Multiscale Discretization Techniques"; • Wednesday Research Kitchen; • Public Lecture by Prof. J¨ornBehrens (KlimaCampus, Universit¨atHamburg) on \Tsunami Fr¨uh-Warnung: Mathematik und Wissenschaftliches Rechnen im Dienste der Sicherheit". We sincerely hope that you enjoy your stay in Linz! Local Organizing Committee Program Committee Robert Scheichl, Bath & RICAM (Chair) Peter Bastian, University of Heidelberg, Germany J¨orgWillems, RICAM (Coordinator) Mike Cullen, Met Office, Exeter, UK Johannes Kraus, RICAM (Co-Coordinator) Heinz Engl, RICAM & University of Vienna, Austria Erwin Karer, RICAM (Co-Coordinator) Melina Freitag, University of Bath, UK Ivan G. Graham, University of Bath, UK Ulrich Langer, RICAM & University of Linz, Austria Markus Melenk, TU Vienna, Austria Robert Scheichl, University of Bath, UK (Chair) Mary F. Wheeler, University of Texas at Austin, USA Contents Information 2 Workshop Information . 2 Social Events . 2 Restaurants and Cafes . 2 General Information . 2 Program 5 Posters 7 Abstracts 8 Abstracts for Posters 17 List of Participants 20 1 Information Workshop Information Registration. The workshop registration will be on November 21st, 2011 from 9:00 - 9:40 am next to the seminar room SP2 416 on the 4th floor of the Science Park Building 2 (see floor plan). Participants that arrive later in the week can register at the special semester office SP2 456. Registration Fee. Non-invited participants are kindly asked to pay the registration fee in cash upon registration. Campus plan and overview map as well as a floor plan of the 4th floor of the workshop venue (Sci- ence Park Building 2) are located on the next pages. Seminar room. The workshop will take place in seminar room SP2 416 on the 4th floor of the Science Park Building 2 (see floor plan). Program. A time schedule for the workshop is located on the backside of this booklet. Coffee breaks. The coffee breaks will be in the corridor of the 4th floor of the Science Park Building 2. Internet access. There will be an extra information sheet regarding internet access available at regis- tration. Social Events Welcome Reception & Poster Session. Monday, November 21st, 2011, 5:15 pm, on the 4th floor of the Science Park Building 2. Conference Dinner. Thursday, November 24th, 2011, 7:00 pm, at the restaurant \Kepler's", situated in the Mensa building Restaurants and Cafes • Mensa Markt (lunch time only) - Main canteen of the University (see campus plan) • KHG Mensa (lunch time only) - Smaller canteen - good traditional food (see overview map: \KHG Linz") • Pizzeria \Bella Casa" - Italian and Greek restaurant (located next to the tram stop) • Chinese restaurant \Jadegarten" - (located close by the tram stop, adjacent to \Bella Casa") • Asia restaurant \A2" - (located behind the Science Park on Altenbergerstrasse) • \Chat" cafe - coffee, drinks and sandwiches (located in the “H¨orsaaltrakt"- see overview map) • Cafe \Sassi" - coffee, drinks and small snacks (located in the building \Johannes Kepler Universit¨at" - see overview map) • Bakery \Kandur" - bakery and small cafe (located opposite the tram stop) General Information Accommodation. The arranged accomodation for invited