Blar i UiS Brage på forfatter "Evje, Steinar"
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A compressible two-phase model with pressure-dependent well-reservoir interaction
Evje, Steinar (Journal article; Peer reviewed, 2013)This paper deals with a two-phase compressible gas-liquid model relevant for modeling of gas-kick flow scenarios in oil wells. To make the model more realistic we include a natural pressure-dependent well-formation ... -
A pore-to-core scale investigation of hysteresis for CO2 storage processes using a discrete-domain method
Engarnevis, Nazila (Master thesis, 2022)In this thesis we have studied a discrete-domain method that is implemented to demonstrate the immiscible, two-phase displacements of two fluids, namely CO2 and water (or brine) in an originally water-saturated reservoir ... -
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 ... -
A Three-Phase Model for Tumor Cell Migration
Urdal, Jone (Masteroppgave/UIS-TN-IEP/2018;, Master thesis, 2018-06)Flow of interstitial fluid (IF) has proven to have a significant effect on the migration of cancer cells through tissue due to the tumor cells ability to sense flow by secreting chemokines that convect in the flow direction ... -
An exponential time-differencing method for monotonic relaxation systems
Aursand, Peder; Evje, Steinar; Flåtten, Tore; Teigen, Knut Erik; Munkejord, Svend Tollak (Journal article; Peer reviewed, 2014)We present first and second-order accurate exponential time differencing methods for a special class of stiff ODEs, denoted as monotonic relaxation ODEs. Some desirable accuracy and robustness properties of our methods are ... -
Analysis of Wired Drill Pipe data while using the Controlled Mud Level technology
El Demerdash Ali, Omar (Master thesis, 2021)Managed Pressure Drilling (MPD) methods are used to drill wells with narrow pressure margins in a safe, efficient, and economical way. Controlled Mud Level (CML) is a dual-gradient MPD technique which is found effective ... -
Asymptotic behavior of a compressible two-phase model with well–formation interaction.
Evje, Steinar; Friis, Helmer Andre (Journal article; Peer reviewed, 2013-02)In this work we consider a compressible gas–liquid model with a well–reservoir interaction term that is relevant for coupled wellbore-reservoir flow systems involved in e.g. drilling operations. Main focus is on deriving ... -
Can cancer cells inform us about the tumor microenvironment?
Nævdal, Geir; Evje, Steinar (Peer reviewed; Journal article, 2023)Characteristics of the tumor microenvironment (TME) such as the leaky intratumoral vascular network and the density and composition of the desmoplastic extracellular matrix (ECM) contain essential information that determine ... -
A compressible viscous three-phase model for porous media flow based on the theory of mixtures
Qiao, Yangyang; Evje, Steinar (Peer reviewed; Journal article, 2020)In this paper we focus on a general model to describe compressible and immiscible three-phase flow in porous media. The underlying idea is to replace Darcy’s law by more general momentum balance equations. In particular, ... -
Fluid-sensitive migration mechanisms predict association between metastasis and high interstitial fluid pressure in pancreatic cancer
Nævdal, Geir; Rofstad, Einar K; Søreide, Kjetil; Evje, Steinar (Peer reviewed; Journal article, 2022)A remarkable feature in pancreatic cancer is the propensity to metastasize early, even for small, early stage cancers. We use a computer-based pancreatic model to simulate tumor progression behavior where fluid-sensitive ... -
Genuine two-phase flow dynamics with a free interface separating gas-liquid mixture from gas
Evje, Steinar (Journal article; Peer reviewed, 2013)This paper deals with a two-phase compressible gas-liquid model relevant for modeling of gas-kick flow scenarios in oil wells. To make the model more realistic we include a natural pressure-dependent well-formation ... -
Global weak solutions for a compressible gas-liquid model with well-formation interaction
Evje, Steinar (Journal article; Peer reviewed, 2011-10)Abstract. The objective of this work is to explore a compressible gas-liquid model designed for modeling of well °ow processes. We build into the model well-reservoir interaction by allowing °ow of gas between well and ... -
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 ... -
How to apply a two-phase model from fluid mechanics to study cell migration mechanisms
Kjørslevik, Trygve Alexander Carlsen (Masteroppgave/UIS-TN-IPT/2016;, Master thesis, 2016-06-15)The classical Keller-Segel model of cell migration due to random motion and chemotaxis, has, as a result of its intuitive simplicity and ability to replicate key behavior of chemotactic populations, provided a foundation ... -
Identification of nonlinear conservation laws for multiphase flow based on Bayesian inversion
Evje, Steinar; Skadsem, Hans Joakim; Nævdal, Geir (Peer reviewed; Journal article, 2023)Conservation laws of the generic form ct+f(c)x=0 play a central role in the mathematical description of various engineering related processes. Identification of an unknown flux function f(c) from observation data in space ... -
Identification of Nonlinear Conservation Laws Using Symbolic Neural Networks
Qing, Li (PhD Theses;731, Doctoral thesis, 2023)Nonlinear dynamical systems are omnipresent in nature, commonly seen in many disciplines such as physics, biology, chemistry, climate science, and engineering. In this thesis, we introduce several new ideas by integrating ... -
Identification of the flux function of nonlinear conservation laws with variable parameters
Li, Qing; Geng, Jiahui; Evje, Steinar (Peer reviewed; Journal article, 2023-09)Machine learning methods have in various ways emerged as a useful tool for modeling the dynamics of physical systems in the context of partial differential equations (PDEs). Nonlinear conservation laws (NCLs) of the form ... -
In silico investigations of intratumoral heterogeneous interstitial fluid pressure
Waldeland, Jahn Otto; Gaustad, Jon-Vidar; Rofstad, Einar K; Evje, Steinar (Peer reviewed; Journal article, 2021-06)Recent preclinical studies have shown that interstitial fluid pressure (IFP) within tumors can be heterogeneous Andersen et al. (2019). In that study tumors of two xenograft models, respectively, HL-16 cervical carcinoma ... -
An Investigation of Second-Order Finite Volume Methods for Field-scale Reservoir Simulation
Kvashchuk, Anna (PhD thesis UiS;, Doctoral thesis, 2024)This thesis focuses on improving the accuracy of numerical simulation of flow in subsurface reservoirs by using second-order finite volume methods. The first-order finite volume method, commonly used in reservoir simulation, ... -
Investigations of Transient Behaviour for non-Newtonian Fluid in a Vertical Well
Tlais, Mohamad Jawad (Master thesis, 2024)One of the most important factors in well-drilling operations is the accurate calculation of friction pressure loss. The accuracy of calculating this factor directly affects the management of bottom hole pressure and erosion ...