Now showing items 41-60 of 814

    • Entropy stable boundary conditions for the Euler equations 

      Svärd, Magnus (Journal article; Peer reviewed, 2021)
      We consider the initial-boundary value Euler equations with the aim to derive boundary conditions that yield an entropy bound for the physical (Navier-Stokes) entropy. We begin by reviewing the entropy bound obtained for ...
    • Udvikling af elevers matematiske forståelse gennem helklassediskussion 

      Dahl, Bettina (Journal article; Peer reviewed, 2021)
      I denne artikel vil jeg på baggrund af udvalgt litteratur og empiri diskutere og give eksempler på, hvordan en matematiklærer kan gennemføre en dialog på klassen. Klasserumsdialoger kritiseres ofte, og somme tider med god ...
    • Iterative Coupling for Fully Dynamic Poroelasticity 

      Bause, Markus; Both, Jakub; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)
      We present an iterative coupling scheme for the numerical approximation of the mixed hyperbolic-parabolic system of fully dynamic poroelasticity. We prove its convergence in the Banach space setting for an abstract ...
    • Temporal Scale-Dependent Sensitivity Analysis for Hydrological Model Parameters Using the Discrete Wavelet Transform and Active Subspaces 

      Bittner, Daniel; Engel, Michael; Wohlmuth, Barbara; Labat, David; Chiogna, Gabriele (Journal article; Peer reviewed, 2021)
      Global sensitivity analysis is an important step in the process of developing and analyzing hydrological models. Measured data of different variables are used to identify the number of sensitive model parameters and to ...
    • A Nonlinear Formulation of Radiation Stress and Applications to Cnoidal Shoaling 

      Paulsen, Martin Oen; Kalisch, Henrik (Journal article; Peer reviewed, 2021)
      In this article, we provide formulations of energy flux and radiation stress consistent with the scaling regime of the Korteweg–de Vries (KdV) equation. These quantities can be used to describe the shoaling of cnoidal waves ...
    • Lagrangian Measurements of Orbital Velocities in the Surf Zone 

      Bjørnestad, Maria; Buckley, M.; Kalisch, Henrik; Streßer, M.; Horstmann, J.; Frøysa, Hege Guldbrandsen; Ige, Olufemi Elijah; Cysewski, M.; Carrasco-Alvarez, R. (Journal article; Peer reviewed, 2021)
      Eulerian and Lagrangian measurements of orbital velocities in waves approaching a beach are analyzed with the goal of understanding the relative influence of wave-by-wave variations in mean-water level, wave height and ...
    • Towards improved monitoring of offshore carbon storage: A real-world field experiment detecting a controlled sub-seafloor CO2 release 

      Flohr, Anita; Schaap, Allison; Achterberg, Eric P.; Alendal, Guttorm; Arundell, Martin; Berndt, Christian; Blackford, Jeremy; Bröttner, Christoph; Borisov, Sergey M.; Brown, Robin; Bull, Jonathan M.; Carter, Liam; Chen, Baixin; Dale, Andrew W.; De Beer, Dirk; Dean, Marcella; Deusner, Christian; Dewar, Marius; Durden, Jennifer M.; Elsen, Saskia; Esposito, Mario; Faggetter, Michael; Fischer, Jan P.; Gana, Amine; Gros, Jonas; Haeckel, Matthias; Hanz, Rudolf; Holtappels, Moritz; Hosking, Brett; Huvenne, Veerle A.I.; James, Rachael H.; Koopmans, Dirk; Kossel, Elke; Leighton, Timothy G.; Li, Jianghui; Lichtschlag, Anna; Linke, Peter; Loucaides, Socratis; Martínez-Cabanas, María; Matter, Juerg M.; Mesher, Thomas; Monk, Samuel; Mowlem, Matthew C.; Oleynik, Anna; Papadimitriou, Stathys; Paxton, David; Pearce, Christopher R.; Peel, Kate; Roche, Ben; Connelly, Douglas (Journal article; Peer reviewed, 2021)
      Carbon capture and storage (CCS) is a key technology to reduce carbon dioxide (CO2) emissions from industrial processes in a feasible, substantial, and timely manner. For geological CO2 storage to be safe, reliable, and ...
    • Identifying Stagnation Zones and Reverse Flow Caused by River-Aquifer Interaction: An Approach Based on Polynomial Chaos Expansions 

      Merchán-Rivera, P.; Wohlmuth, Barbara Irmgard; Chiogna, Gabriele (Journal article; Peer reviewed, 2021)
      Fluctuating stream stages and peak-flow events can significantly influence the interactions between streams and aquifers and modify the hydraulic gradient, the flux exchange and the subsurface flow paths. As a result, ...
    • Global random walk solvers for fully coupled flow and transport in saturated/unsaturated porous media 

      Suciu, Nicolae; Illiano, Davide; Prechtel, Alexander; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)
      In this article, we present new random walk methods to solve flow and transport problems in saturated/unsaturated porous media, including coupled flow and transport processes in soils, heterogeneous systems modeled through ...
    • Modeling of relative permeabilities including dynamic wettability transition zones 

      Kassa, Abay; Gasda, Sarah E.; Kumar, Kundan; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)
      Wettability is a pore-scale property that impacts the relative movement and distribution of fluids in a porous medium. There are reservoir fluids that provoke the surface within pores to undergo a wettability change. This ...
    • A Mixed Approach to the Poisson Problem with Line Sources 

      Gjerde, Ingeborg Gåseby; Kumar, Kundan; Nordbotten, Jan Martin (Journal article; Peer reviewed, 2021)
      In this work we consider the dual-mixed variational formulation of the Poisson equation with a line source. The analysis and approximation of this problem is nonstandard, as the line source causes the solutions to be ...
    • Reducing the domination number of graphs via edge contractions and vertex deletions 

      Galby, Esther; Lima, Paloma T.; Ries, Bernard (Journal article; Peer reviewed, 2021)
      In this work, we study the following problem: given a connected graph G, can we reduce the domination number of G by at least one using k edge contractions, for some fixed integer k>0? We show that for k=1 (resp. k=2), the ...
    • Quenched invariance principle for random walks on dynamically averaging random conductances 

      Bethuelsen, Stein Andreas; Hirsch, Christian; Mönch, Christian (Journal article; Peer reviewed, 2021)
      We prove a quenched invariance principle for continuous-time random walks in a dynamically averaging environment on Z. In the beginning, the conductances may fluctuate substantially, but we assume that as time proceeds, ...
    • Students’ evaluation of academic courses: An exploratory analysis to an Italian case study 

      Centoni, Marco; Maruotti, Antonello (Journal article; Peer reviewed, 2021)
      Students’ evaluations of teaching is a common practice in higher education institutions, with the main purpose of improving course quality and effectiveness. In this paper we would like to contribute to the existing ...
    • A lagrangian approach to extremal curves on stiefel manifolds 

      Hüper, Knut; Markina, Irina; Leite, Fátima Silva (Journal article; Peer reviewed, 2021)
      A unified framework for studying extremal curves on real Stiefel manifolds is presented. We start with a smooth one-parameter family of pseudo-Riemannian metrics on a product of orthogonal groups acting transitively on ...
    • Dimensional reduction of a fractured medium for a polymer EOR model 

      Dugstad, Martin Sandanger; Kumar, Kundan; Pettersen, Øystein (Journal article; Peer reviewed, 2021)
      Dimensional reduction strategy is an effective approach to derive reliable conceptual models to describe flow in fractured porous media. The fracture aperture is several orders of magnitude smaller than the characteristic ...
    • Brain solute transport is more rapid in periarterial than perivenous spaces 

      Vinje, Vegard; Bakker, Erik N. T. P.; Rognes, Marie Elisabeth (Journal article; Peer reviewed, 2021)
      Fluid flow in perivascular spaces is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular ...
    • Ill-posedness of the Maxwell–Dirac system below charge in space dimension three and lower 

      Selberg, Sigmund; Tesfahun, Achenef (Journal article; Peer reviewed, 2021)
      The Maxwell–Dirac system describes the interaction of an electron with its self-induced electromagnetic field. In space dimension d=3 the system is charge-critical, that is, L2-critical for the spinor with respect to ...
    • Well-posedness and discretization for a class of models for mixed-dimensional problems with high-dimensional gap 

      Hodneland, Erlend; Hu, Xiaozhe; Nordbotten, Jan Martin (Journal article; Peer reviewed, 2021)
      In this work, we show the underlying mathematical structure of mixed-dimensional models arising from the composition of graphs and continuous domains. Such models are becoming popular in applications, in particular, to ...
    • Robust Linear Domain Decomposition Schemes for Reduced Nonlinear Fracture Flow Models 

      Ahmed, Elyes; Fumagalli, Alessio; Budisa, Ana; Keilegavlen, Eirik; Nordbotten, Jan Martin; Radu, Adrian Florin (Journal article; Peer reviewed, 2021)
      In this work, we consider compressible single-phase flow problems in a porous medium containing a fracture. In the fracture, a nonlinear pressure-velocity relation is prescribed. Using a non-overlapping domain decomposition ...