Browsing Bergen Open Research Archive by Author "Radu, Florin Adrian"
Now showing items 1-20 of 24
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An accelerated staggered scheme for variational phase-field models of brittle fracture
Storvik, Erlend; Both, Jakub Wiktor; Sargado, Juan Michael Uy Villanueva; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)There is currently an increasing interest in developing efficient solvers for variational phase-field models of brittle fracture. The governing equations for this problem originate from a constrained minimization of a ... -
Adaptive asynchronous time-stepping, stopping criteria, and a posteriori error estimates for fixed-stress iterative schemes for coupled poromechanics problems
Ahmed, Elyes; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2020)In this paper we develop adaptive iterative coupling schemes for the Biot system modeling coupled poromechanics problems. We particularly consider the space–time formulation of the fixed-stress iterative scheme, in which ... -
A convergent mass conservative numerical scheme based on mixed finite elements for two-phase flow in porous media
Radu, Florin Adrian; Kumar, Kundan; Nordbotten, Jan Martin; Pop, Sorin Iuliu (Research report, 2017)In this work we present a mass conservative numerical scheme for two-phase flow in porous media. The model for flow consists on two fully coupled, non-linear equations: a degenerate parabolic equation and an elliptic ... -
The Fixed-Stress splitting scheme for Biot's equations as a modified Richardson iteration: Implications for optimal convergence
Storvik, Erlend; Both, Jakub; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)The fixed-stress splitting scheme is a popular method for iteratively solving the Biot equations. The method successively solves the flow and mechanics subproblems while adding a stabilizing term to the flow equation, which ... -
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 ... -
Higher order space-time elements for a non-linear Biot model
Borregales Reveron, Manuel Antonio; Radu, Florin Adrian (Lecture Notes in Computational Science and Engineering ; 126, Conference object; Peer reviewed; Book, 2019)In this work, we consider a non-linear extension of the linear, quasi-static Biot’s model. Precisely, we assume that the volumetric strain and the fluid compressibility are non-linear functions. We propose a fully discrete ... -
Impact of time-dependent wettability alteration on the dynamics of capillary pressure
Kassa, Abay; Gasda, Sarah; Kumar, Kundan; Radu, Florin Adrian (Journal article; Peer reviewed, 2020)Wettability is a pore-scale property that has an important impact on capillarity, residual trapping, and hysteresis in porous media systems. In many applications, the wettability of the rock surface is assumed to be constant ... -
Implicit linearization scheme for nonstandard two-phase flow in porous media
Kassa, Abay; Kumar, Kundan; Gasda, Sarah; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)In this article, we consider a nonlocal (in time) two‐phase flow model. The nonlocality is introduced through the wettability alteration induced dynamic capillary pressure function. We present a monotone fixed‐point iterative ... -
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 ... -
Iterative Linearisation Schemes for Doubly Degenerate Parabolic Equations
Both, Jakub; Kumar, Kundan; Nordbotten, Jan Martin; Pop, Iuliu Sorin; Radu, Florin Adrian (Conference object; Peer reviewed; Journal article, 2019)Mathematical models for flow and reactive transport in porous media often involve non-linear, degenerate parabolic equations. Their solutions have low regularity, and therefore lower order schemes are used for the numerical ... -
Iterative schemes for surfactant transport in porous media
Illiano, Davide; Pop, Iuliu Sorin; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)In this work, we consider the transport of a surfactant in variably saturated porous media. The water flow is modelled by the Richards equations and it is fully coupled with the transport equation for the surfactant. Three ... -
Iterative solvers for Biot model under small and large deformation
Borregales Reveron, Manuel Antonio; Kumar, Kundan; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)We consider L-scheme and Newton-based solvers for Biot model under large deformation. The mechanical deformation follows the Saint Venant-Kirchoff constitutive law. Furthermore, the fluid compressibility is assumed to be ... -
Iterative splitting schemes for a soft material poromechanics model
Both, Jakub Wiktor; Barnafi, Nicolas; Radu, Florin Adrian; Zunino, Paolo; Quarteroni, Alfio (Journal article; Peer reviewed, 2021)We address numerical solvers for a poromechanics model particularly adapted for soft materials, as it generally respects thermodynamics principles and energy balance. Considering the multi-physics nature of the problem, ... -
An iterative staggered scheme for phase field brittle fracture propagation with stabilizing parameters
Brun, Mats Kirkesæther; Wick, Thomas; Berre, Inga; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2020)This paper concerns the analysis and implementation of a novel iterative staggered scheme for quasi-static brittle fracture propagation models, where the fracture evolution is tracked by a phase field variable. The model ... -
Mathematics and Medicine: How mathematics, modelling and simulations can lead to better diagnosis and treatments
Hanson, Erik Andreas; Hodneland, Erlend; Lorentzen, Rolf Johan; Nævdal, Geir; Nordbotten, Jan Martin; Sævareid, Ove; Zanna, Antonella (Lecture Notes in Computational Science and Engineering, Chapter; Peer reviewed; Journal article, 2019)Starting with the discovery of X-rays by Röntgen in 1895, the progress in medical imaging has been extraordinary and immensely beneficial to diagnosis and therapy. Parallel to the increase of imaging accuracy, there is the ... -
Microfluidic study of effects of flow velocity and nutrient concentration on biofilm accumulation and adhesive strength in the flowing and no-flowing microchannels
Liu, Na; Skauge, Tormod; Landa-Marbán, David; Hovland, Beate; Thorbjørnsen, Bente; Radu, Florin Adrian; Vik, Bartek Florczyk; Baumann, Thomas; Bødtker, Gunhild (Journal article; Peer reviewed, 2019)Biofilm accumulation in porous media can cause pore plugging and change many of the physical properties of porous media. Engineering bioplugging may have significant applications for many industrial processes, while improved ... -
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 ... -
Monolithic and splitting solution schemes for fully coupled quasi-static thermo-poroelasticity with nonlinear convective transport
Brun, Mats Kirkesæther; Ahmed, Elyes; Berre, Inga; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2020)This paper concerns monolithic and splitting-based iterative procedures for the coupled nonlinear thermo-poroelasticity model problem. The thermo-poroelastic model problem we consider is formulated as a three-field system ... -
On the optimization of the fixed‐stress splitting for Biot's equations
Storvik, Erlend; Both, Jakub; Kumar, Kundan; Nordbotten, Jan Martin; Radu, Florin Adrian (Peer reviewed; Journal article, 2019)In this work, we are interested in efficiently solving the quasi‐static, linear Biot model for poroelasticity. We consider the fixed‐stress splitting scheme, which is a popular method for iteratively solving Biot's equations. ... -
A pore-scale model for permeable biofilm: Numerical simulations and laboratory experiments
Landa-Marban, David; Liu, Na; Pop, Iuliu Sorin; Kumar, Kundan; Pettersson, Per; Bødtker, Gunhild; Skauge, Tormod; Radu, Florin Adrian (Peer reviewed; Journal article, 2019)In this paper, we derive a pore-scale model for permeable biofilm formation in a two-dimensional pore. The pore is divided into two phases: water and biofilm. The biofilm is assumed to consist of four components: water, ...