Blar i UiS Brage på forfatter "Friis, Helmer André"
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A Study of a Mathematical Model for Cancer Cell Growth in a Gel
Vegge, David (Master thesis, 2017-06-15)In this thesis, a mathematical model describing gel contraction is derived and studied. The mathematical model describes the process where cells are compressing the gel, and the model is therefore used to study the cell ... -
Adaptive mesh refinement in locally conservative level set methods for multiphase fluid displacements in porous media
Singh, Deepak; Friis, Helmer André; Jettestuen, Espen; Helland, Johan Olav (Peer reviewed; Journal article, 2023)Multiphase flow in porous media often occurs with the formation and coalescence of fluid ganglia. Accurate predictions of such mechanisms in complex pore geometries require simulation models with local mass conservation ... -
Global weak solutions for a gas liquid model with external forces and general pressure law
Evje, Steinar; Friis, Helmer André (Journal article; Peer reviewed, 2011)In this work we show existence of global weak solutions for a two-phase gas-liquid model where the gas phase is represented by a general isothermal pressure law, whereas the liquid is assumed to be incompressible. To make ... -
A level set approach to Ostwald ripening of trapped gas bubbles in porous media
Singh, Deepak; Friis, Helmer André; Jettestuen, Espen; Helland, Johan Olav (Peer reviewed; Journal article, 2022)Ostwald ripening of gas bubbles is a thermodynamic process for mass transfer, which is important for both foam enhanced oil recovery and geological CO2 storage. We present a methodology for simulating Ostwald ripening of ... -
Numerical treatment of two-phase flow in capillary heterogeneous porous media by finite-volume approximations
Evje, Steinar; Friis, Helmer André (Journal article; Peer reviewed, 2012)This paper examines two-phase flow in porous media with heterogeneous capillary pressure functions. This problem has received very little attention in the literature, and constitutes a challenge for numerical discretization, ... -
Pore-scale Ostwald ripening of gas bubbles in the presence of oil and water in porous media
Singh, Deepak; Friis, Helmer André; Jettestuen, Espen; Helland, Johan Olav (Peer reviewed; Journal article, 2023)Hypothesis Ostwald ripening of gas bubbles is a spontaneous mass transfer process that can impact the storage volume of trapped gas in the subsurface. In homogeneous porous media with identical pores, bubbles evolve toward ... -
Prediction of Optimal Production Time during Underground CH4 Storage with Cushion CO2 Using Reservoir Simulations and Artificial Neural Networks
Helland, Johan Olav; Friis, Helmer André; Assadi, Mohsen; Klimkowski, Lukasz; Nagy, Stanislaw (Peer reviewed; Journal article, 2023)Injection of carbon dioxide (CO2) in aquifers for underground natural gas storage (UNGS) can improve the operating efficiency of the storage facility during gas injection and production and later serve as a solution for ...