Gaute Linga

• Shafabakhsh, Paiman; Cordonnier, Benoit; Pluymakers, Anne Marie Henriette; Le Borgne, Tanguy; Mathiesen, Joachim & Linga, Gaute [Vis alle 9 forfattere av denne artikkelen] (2024). 4D Neutron Imaging of Solute Transport and Fluid Flow in Sandstone Before and After Mineral Precipitation. Water Resources Research. ISSN 0043-1397. 60(3). doi: 10.1029/2023WR036293.
• Dziadkowiec, Joanna; Linga, Gaute; Kalchgruber, Lukas; Kavunga, Sunil; Cheng, Hsiu-Wei & Nilsen, Ola [Vis alle 9 forfattere av denne artikkelen] (2024). Electrochemically Assisted Growth of Hopper and Tabular Calcite under Confinement. Crystal Growth & Design. ISSN 1528-7483. doi: 10.1021/acs.cgd.3c01433. Fulltekst i vitenarkiv
• Linga, Gaute; Mathiesen, Joachim; Renard, Francois & Le Borgne, Tanguy (2023). Fingerprints of Chaos in a Two-Phase Porous Media Flow. I Médici, Ezequiel F. & Otero, Alejandro D. (Red.), Album of Porous Media. Springer. ISSN 978-3-031-23800-0. doi: 10.1007/978-3-031-23800-0_64.
• Kozlowski Pitombeira Reis, Paula; Moura, Marcel; Linga, Gaute; Rikvold, Per Arne; Toussaint, Renaud & Flekkøy, Eirik Grude [Vis alle 7 forfattere av denne artikkelen] (2023). A simplified pore-scale model for slow drainage including film-flow effects. Advances in Water Resources. ISSN 0309-1708. 182. doi: 10.1016/j.advwatres.2023.104580. Fulltekst i vitenarkiv
• Kozlowski Pitombeira Reis, Paula; Moura, Marcel; Linga, Gaute; Rikvold, Per Arne; Flekkøy, Eirik Grude & Måløy, Knut Jørgen (2023). A simplified pore-scale model for slow drainage including film-flow effects. arXiv.org. ISSN 2331-8422. doi: 10.48550/arXiv.2303.03064.
• Mathiesen, Joachim; Linga, Gaute; Misztal, Marek; Renard, Francois & Le Borgne, Tanguy (2023). Dynamic Fluid Connectivity Controls Solute Dispersion in Multiphase Porous Media Flow. Geophysical Research Letters. ISSN 0094-8276. 50(16). doi: 10.1029/2023GL105233. Fulltekst i vitenarkiv
• Baldelli, Beatrice; Linga, Gaute & Flekkøy, Eirik Grude (2022). Thermal conduction through a cool well. Physical Review Fluids. ISSN 2469-990X. 7(10). doi: 10.1103/PhysRevFluids.7.103503. Fulltekst i vitenarkiv
• Linga, Gaute; Angheluta, Luiza & Mathiesen, Joachim (2022). Onset of turbulence in channel flows with scale-invariant roughness. Physical Review Research (PRResearch). ISSN 2643-1564. 4(3). doi: 10.1103/PhysRevResearch.4.033086. Fulltekst i vitenarkiv
• Haugerud, Ivar Svalheim; Linga, Gaute & Flekkøy, Eirik Grude (2022). Solute dispersion in channels with periodic square boundary roughness. Journal of Fluid Mechanics. ISSN 0022-1120. 944. doi: 10.1017/jfm.2022.522. Fulltekst i vitenarkiv
• Nielsen, Bjarke Frost; Linga, Gaute; Christensen, Amalie & Mathiesen, Joachim (2020). Substrate curvature governs texture orientation in thin films of smectic block copolymers. Soft Matter. ISSN 1744-683X. 16(14), s. 3395–3406. doi: 10.1039/c9sm02389e. Fulltekst i vitenarkiv
• Linga, Gaute; Bolet, Asger & Mathiesen, Joachim (2020). Transient electrohydrodynamic flow with concentration-dependent fluid properties: Modelling and energy-stable numerical schemes. Journal of Computational Physics. ISSN 0021-9991. 412. doi: 10.1016/j.jcp.2020.109430. Fulltekst i vitenarkiv Vis sammendrag

  Transport of electrolytic solutions under influence of electric fields occurs in phenomena ranging from biology to geophysics. Here, we present a continuum model for single-phase electrohydrodynamic flow, which can be derived from fundamental thermodynamic principles. This results in a generalized Navier–Stokes–Poisson–Nernst–Planck system, where fluid properties such as density and permittivity depend on the ion concentration fields. We propose strategies for constructing numerical schemes for this set of equations, where the electrochemical and the hydrodynamic subproblems are decoupled at each time step. We provide time discretizations of the model that suffice to satisfy the same energy dissipation law as the continuous model. In particular, we propose both linear and non-linear discretizations of the electrochemical subproblem, along with a projection scheme for the fluid flow. The efficiency of the approach is demonstrated by numerical simulations using several of the proposed schemes.

• Linga, Gaute; Møyner, Olav; Nilsen, Halvor Møll; Arthur, Moncorgé & Lie, Knut-Andreas (2020). An implicit local time-stepping method based on cell reordering for multiphase flow in porous media. Journal of Computational Physics: X. ISSN 2590-0552. 6. doi: 10.1016/j.jcpx.2020.100051. Fulltekst i vitenarkiv Vis sammendrag

  We discuss how to introduce local time-step refinements in a sequential implicit method for multiphase flow in porous media. Our approach relies heavily on causality-based optimal ordering, which implies that cells can be ordered according to total fluxes after the pressure field has been computed, leaving the transport problem as a sequence of ordinary differential equations, which can be solved cell-by-cell or block-by-block. The method is suitable for arbitrary local time steps and grids, is mass-conservative, and reduces to the standard implicit upwind finite-volume method in the case of equal time steps in adjacent cells. The method is validated by a series of numerical simulations. We discuss various strategies for selecting local time steps and demonstrate the efficiency of the method and several of these strategies by through a series of numerical examples.

• Linga, Gaute & Flåtten, Tore Halsne (2019). A Hierarchy of Non-Equilibrium Two-Phase Flow Models. ESAIM: Proceedings and Surveys. ISSN 2267-3059. 66, s. 109–143. doi: 10.1051/proc/201966006. Fulltekst i vitenarkiv Vis sammendrag

  We review and extend a hierarchy of relaxation models for two-phase flow. The models are derived from the non-equilibrium Baer–Nunziato model, which is endowed with relaxation source terms to drive it towards equilibrium. The source terms cause transfer of volume, heat, mass and momentum due to differences between the phases in pressure, temperature, chemical potential and velocity, respectively. In the context of two-phase flow models, the subcharacteristic condition implies that the sound speed of an equilibrium system can never exceed that of the relaxation system. Here, previous work by Flåtten and Lund [Math. Models Methods Appl. Sci., 21 (12), 2011, 2379–2407] and Lund [SIAM J. Appl. Math. 72, 2012, 1713–1741] is extended to encompass two-fluid models, i.e. models with separately governed velocities for the two phases. Each remaining model in the hierarchy is derived, and analytical expressions for the sound speeds are presented. Given only physically fundamental assumptions, the subcharacteristic condition is shown to be satisfied in the entire hierarchy, either in a weak or in a strong sense.

• Linga, Gaute; Bolet, Asger & Mathiesen, Joachim (2019). Bernaise: A flexible framework for simulating two-phase electrohydrodynamic flows in complex domains. Frontiers in Physics. ISSN 2296-424X. 7. doi: 10.3389/fphy.2019.00021.
• Linga, Gaute; Bolet, Asger & Mathiesen, Joachim (2018). Controlling wetting with electrolytic solutions: Phase-field simulations of a droplet-conductor system. Physical Review E (PRE). ISSN 2470-0045. 98(1). doi: 10.1103/PhysRevE.98.013101.
• Bolet, Asger; Linga, Gaute & Mathiesen, Joachim (2018). Electrohydrodynamic channeling effects in narrow fractures and pores. Physical Review E (PRE). ISSN 2470-0045. 97(4). doi: 10.1103/PhysRevE.97.043114.
• Linga, Gaute; Mathiesen, Joachim & Renard, Francois (2017). Self-similar distributions of fluid velocity and stress heterogeneity in a dissolving porous limestone. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 122(3), s. 1726–1743. doi: 10.1002/2016JB013536. Fulltekst i vitenarkiv
• Wilhelmsen, Øivind; Aasen, Ailo; Skaugen, Geir; Aursand, Peder; Austegard, Anders & Aursand, Eskil [Vis alle 10 forfattere av denne artikkelen] (2017). Thermodynamic modeling with equations of state: present challenges with established methods. Industrial & Engineering Chemistry Research. ISSN 0888-5885. 56(13), s. 3503–3515. doi: 10.1021/acs.iecr.7b00317. Fulltekst i vitenarkiv Vis sammendrag

  Equations of state (EoS) are essential in the modeling of a wide range of industrial and natural processes. Desired qualities of EoS are accuracy, consistency, computational speed, robustness and predictive ability outside of the domain where they have been fitted. In this work, we review present challenges associated with established models, and give suggestions on how to overcome them in the future. The most accurate EoS available, multiparameter EoS, have a second artificial Maxwell loop in the two-phase region that gives problems in phase-equilibrium calculations and exclude them from important applications such as treatment of interfacial phenomena with mass based density functional theory. Suggestions are provided on how this can be improved. Cubic EoS are among the most computationally efficient EoS, but they often lack sufficient accuracy. We show that extended corresponding state EoS are capable of providing significantly more accurate single-phase predictions than cubic EoS with only a doubling of the computational time. In comparison, the computational time of multiparameter EoS can be orders of magnitude larger. For mixtures in the two-phase region, however, the accuracy of extended corresponding state EoS has a large potential for improvement. The molecular-based SAFT family of EoS are preferred when predictive ability is important, e.g. for systems with strongly associating fluids or polymers where few experimental data are available. We discuss some of their benefits and present challenges. A discussion is presented on why predictive thermodynamic models for reactive mixtures such as CO2-NH3 and CO2-H2O-H2S must be developed in close combination with phase- and reaction equilibrium theory, regardless of the choice of EoS. After overcoming present challenges, a next-generation thermodynamic modeling framework holds the potential to improve the accuracy and predictive ability in a wide range of applications such as process optimization, computational fluid dynamics, treatment of interfacial phenomena and processes with reactive mixtures.

• Linga, Gaute & Lund, Halvor (2016). A Two-Fluid Model for Vertical Flow Applied to CO2 Injection Wells. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 51, s. 71–80. doi: 10.1016/j.ijggc.2016.05.009. Fulltekst i vitenarkiv Vis sammendrag

  Flow of CO2 in wells is associated with substantial variations in thermophysical properties downhole, due to the coupled transient processes involved: complex flow patterns, density changes, phase transitions, and heat transfer to and from surroundings. Large temperature variations can lead to thermal stresses and subsequent loss of well integrity, and it is therefore crucial to employ models that can predict this accurately. In this work, we present a model for vertical well flow that includes both two-phase flow and heat conduction. The flow is described by a two-fluid model, where mass transfer between the phases is modelled by relaxation source terms that drive the phases towards thermodynamic equilibrium. We suggest a new formulation of the mass transfer process that satisfies the second law of thermodynamics, and that is also continuous in the single-phase limit. This provides a more robust transition from two-phase to single-phase flow than the previous formulation. The model predicts which flow regimes are present downhole, and calculates friction and heat transfer depending on this. Moreover, the flow model is coupled with a heat conduction model for the layers that comprise the well, including tubing, packer fluid, casing, cement or drilling mud, and rock formation. This enables prediction of the temperature in the well fluid and in each layer of the well. The model is applied to sudden shut-in and blowout cases of a CO2 injection well, where we employ the highly accurate Span-Wagner reference equation-of-state to describe the thermodynamics of CO2. We predict pressure, temperature and flow regimes during these cases and discuss implications for well integrity. © 2016 Elsevier Ltd.

• Linga, Gaute; Ballone, Pietro & Hansen, Alex (2015). Creep rupture of fiber bundles: A molecular dynamics investigation. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. ISSN 1539-3755. 92(2). doi: 10.1103/PhysRevE.92.022405.
• Linga, Gaute; Aursand, Peder & Flåtten, Tore (2015). Two-phase nozzle flow and the subcharacteristic condition. Journal of Mathematical Analysis and Applications. ISSN 0022-247X. 426(2), s. 917–934. doi: 10.1016/j.jmaa.2015.01.065. Vis sammendrag

  We consider nozzle flow models for two-phase flow with phase transfer. Such models are based on energy considerations applied to the frozen and equilibrium limits of the underlying relaxation models. In this paper, we provide an explicit link between the mass flow rate predicted by these models and the classical subcharacteristic condition of Chen, Levermore and Liu. In particular, we demonstrate that for sufficiently small pressure differences, the equilibrium nozzle model will predict a lower mass flow rate than the frozen model when the subcharacteristic condition is satisfied. An application to tank leakage of CO2 is presented, indicating that the frozen and equilibrium models provide significantly different predictions. This difference is comparable in magnitude to the modeling error introduced by applying simple ideal-gas/incompressible-liquid equations-of-state for CO2.

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• Pierce, James Kevin; Moura, Marcel & Linga, Gaute (2023). Chaotic mixing in two-dimensional unsteady porous media flow.
• Pierce, James Kevin; Linga, Gaute & Moura, Marcel (2023). Hallmarks of chaotic mixing in two dimensional unsteady porous media flow.
• Pierce, James Kevin; Linga, Gaute & Moura, Marcel (2023). Impact of the solid structure on solute mixing in porous media flow.
• Pierce, James Kevin & Linga, Gaute (2023). Chaos in flatland: mixing in unsteady two dimensional porous media flow.
• Kozlowski Pitombeira Reis, Paula; Moura, Marcel; Linga, Gaute; Rikvold, Per Arne; Flekkøy, Eirik Grude & Måløy, Knut Jørgen (2023). A modified-invasion-percolation model for drainage in quasi-2D porous media.
• Kozlowski Pitombeira Reis, Paula; Moura, Marcel; Linga, Gaute; Rikvold, Per Arne; Flekkøy, Eirik Grude & Måløy, Knut Jørgen (2023). A simplified pore-scale model for drainage including film flow effects.
• Kozlowski Pitombeira Reis, Paula; Moura, Marcel; Linga, Gaute; Rikvold, Per Arne; Toussaint, Renaud & Flekkøy, Eirik Grude [Vis alle 7 forfattere av denne artikkelen] (2023). Numerical analysis of drainage in porous media using network models.
• Kozlowski Pitombeira Reis, Paula; Moura, Marcel; Linga, Gaute; Rikvold, Per Arne; Flekkøy, Eirik Grude & Måløy, Knut Jørgen (2023). A simplified pore-scale model for slow drainage including film-flow effects.
• Linga, Gaute (2022). Chaotic mixing in intermittent two-phase porous media flows.
• Linga, Gaute; Mathiesen, Joachim; Renard, Francois & Le Borgne, Tanguy (2022). Chaotic mixing in intermittent two-phase porous media flows.
• Linga, Gaute (2020). Stretching and mixing in two-phase flow in porous media.
• Frost Nielsen, Bjarke; Linga, Gaute; Olsen, Kristian Stølevik & Simonsen, Lone (2020). Vejen til frihed. Weekendavisen. ISSN 0106-4142. Vis sammendrag

  https://www.weekendavisen.dk/2020-19/ideer/vejen-til-frihed

• Linga, Gaute; Mathiesen, Joachim; Renard, Francois & Le Borgne, Tanguy (2020). Stretching and Folding in Intermittent Two-Phase Porous Media Flows.
• Linga, Gaute (2019). Two-phase electrohydrodynamics in complex geometries – modelling and simulation.
• Linga, Gaute (2019). Influence of roughness, inertia and surface charge on fluid transport in fractures and pores: Insights from direct numerical simulations.
• Lie, Knut-Andreas; Linga, Gaute; Møyner, Olav; Nilsen, Halvor Møll & Moncorge, A (2019). An implicit local time-stepping method based on cell reordering for multiphase flow in porous media.

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