Mihailo Jankov

• Brodin, Joachim Falck; Pierce, James Kevin; Reis, Paula Kozlowski Pitombeira; Rikvold, Per Arne; Moura, Marcel & Jankov, Mihailo [Vis alle 7 forfattere av denne artikkelen] (2025). Interface instability of two-phase flow in a three-dimensional porous medium. Physical Review Fluids. 10(6). doi: 10.1103/hm82-167x. Fulltekst i vitenarkiv Vis sammendrag

  We present an experimental study of immiscible, two-phase fluid flow through a three-dimensional porous medium consisting of randomly packed, monodisperse glass spheres. Our experiments combine refractive-index matching and laser-induced fluorescence imaging to resolve the morphology and stability of the moving interface resulting from the injection of one fluid into another. The imposed injection rate sets a balance between gravitational and viscous forces, producing interface morphologies which range from unstable collections of tangled fingers at low rates to stable sheets at high rates. The image data are complemented by time-resolved pressure measurements. We develop a stability criterion for the fluid interface based on the analysis of the 3D images and the pressure data. This criterion involves the Darcy permeability in each of the two phases and the time derivative of the pressure drop across the medium. We observe that the relative permeability encountered by the invading fluid is modified by the imposed flow rate in our experiment, which impacts the two-phase flow dynamics. We show that, in addition to the balance between the relevant forces driving the dynamics, local regions of crystalline order in the beadpack (crystallites) affect the stability of the invading front. This work provides insights into how disorder on multiple length scales in porous media can interact with viscous, capillary, and gravitational forces to determine the stability and dynamics of immiscible fluid interfaces.

• Eriksen, Fredrik Kvalheim; Moura, Marcel; Jankov, Mihailo; Turquet, Antoine Leo & Måløy, Knut Jørgen (2022). Transition from viscous fingers to compact displacement during unstable drainage in porous media. Physical Review Fluids. 7(1). doi: 10.1103/PhysRevFluids.7.013901. Fulltekst i vitenarkiv Vis sammendrag

  We describe a crossover from the viscous fingering instability to a compact invasion regime during viscously unstable drainage of porous media, and we investigate the underlying mechanisms of this compact fluid displacement. The study is based on a series of drainage experiments in a radial porous Hele-Shaw cell where we systematically vary the viscosity of the defending (wetting) fluid and the overpressure of the invading (nonwetting) fluid to map out the resulting invasion structures as a function of viscosity ratio and injection pressure. We show that above a threshold of injection pressure and viscosity ratio a more stable and compact invasion structure emerges within the viscous fingering patterns, i.e., a roughly circular displacement with viscous fingers on the outside. The onset of the stable displacement is found to begin at a rather low viscosity ratio M between the invading and defending fluids, i.e., when M≥10−3 for injection pressures of 3–5 kPa. We find that the ratio between the length of the outer fingers and the size of the compact invasion scales with the viscosity ratio and approaches a more or less constant value during growth, resulting in structures with proportionate growth and larger compact invasions for higher viscosity ratios. As opposed to the viscous fingering instability, we describe rich ganglion dynamics within the compact invasion structures and show that the pressure gradient is not screened by the outer fingers.

• Toussaint, R; Måløy, Knut Jørgen; Meheust, Y; Løvoll, Grunde; Jankov, Mihailo & Schäfer, G. [Vis alle 7 forfattere av denne artikkelen] (2012). Two-Phase Flow: Structure, Upscaling, and Consequences for Macroscopic Transport Proper. Vadose Zone Journal. 11(3). doi: 10.2136/vzj2011.0123. Fulltekst i vitenarkiv
• Løvoll, Grunde; Jankov, Mihailo; Måløy, Knut Jørgen; Toussaint, Renaud; Schmittbuhl, J. & Schäfer, G. [Vis alle 7 forfattere av denne artikkelen] (2011). Influence of Viscous Fingering on Dynamic Saturation-Pressure Curves in Porous Media. Transport in Porous Media. ISSN 0169-3913. 86(1), s. 335–354. doi: 10.1007/s11242-010-9622-8. Fulltekst i vitenarkiv
• Jankov, Mihailo; Løvoll, Grunde; Knudsen, Henning Arendt; Måløy, Knut Jørgen; Planet, R & Toussaint, Renaud [Vis alle 7 forfattere av denne artikkelen] (2010). Effects of Pressure Oscillations on Drainage in an Elastic Porous Medium. Transport in Porous Media. ISSN 0169-3913. 84(3), s. 569–585. doi: 10.1007/s11242-009-9521-z. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Moura, Marcel; Brodin, Joachim Falck; Reis, Paula Kozlowski Pitombeira; Pierce, Kevin; Jankov, Mihailo & Rikvold, Per Arne [Vis alle 11 forfattere av denne artikkelen] (2026). From Thin Films to Stable Fronts: Tabletop Experimental Approaches to 2D and 3D Porous Media Flows. doi: https:/www.youtube.com/live/bSQ-sHK6FTU?si=W9_rbJ5BkyRPHP0m. Fulltekst i vitenarkiv
• Brodin, Joachim Falck; Moura, Marcel; Pierce, James Kevin; Reis, Paula Kozlowski Pitombeira; Rikvold, Per Arne & Jankov, Mihailo [Vis alle 7 forfattere av denne artikkelen] (2025). Experimental Investigation of Two-Phase Flow with a Table-Top Optical Scanner: Interface Instability in a Three-Dimensional Porous Medium. Fulltekst i vitenarkiv
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Jankov, Mihailo; Turquet, Antoine Leo; Hansen, Alex & Måløy, Knut Jørgen (2024). Experiments on transient and steady-state flows in porous media: the transition from viscous fingers to compact displacement during unstable drainage flows. Fulltekst i vitenarkiv
• Khobaib, Khobaib; Reis, Paula Kozlowski Pitombeira; Jankov, Mihailo; Moura, Marcel & Måløy, Knut Jørgen (2023). Experimental studies of slow drainage in porous media: Effect of the randomness of the porous medium on the fluid flow. Fulltekst i vitenarkiv
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Jankov, Mihailo; Turquet, Antoine Leo & Måløy, Knut Jørgen (2022). Transition from viscous Fingers to compact displacement during unstable drainage in porous media. Fulltekst i vitenarkiv
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Jankov, Mihailo; Turquet, Antoine Léo & Måløy, Knut Jørgen (2022). Transition from viscous fingers to compact displacement during unstable drainage in porous media. Fulltekst i vitenarkiv
• Moura, Marcel; Brodin, Joachim Falck; Måløy, Knut Jørgen; Rikvold, Per Arne; Flekkøy, Eirik Grude & Jankov, Mihailo [Vis alle 8 forfattere av denne artikkelen] (2022). Thin film flow: fluid transport and pollution spreading in porous media. Fulltekst i vitenarkiv
• Moura, Marcel; Reis, Paula Kozlowski Pitombeira; Eriksen, Fredrik Kvalheim; Turquet, Antoine Léo; Flekkøy, Eirik Grude & Toussaint, Renaud [Vis alle 8 forfattere av denne artikkelen] (2022). Complexity: “More is Different” also in porous media flows. Fulltekst i vitenarkiv
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Jankov, Mihailo; Turquet, Antoine Léo & Måløy, Knut Jørgen (2022). Transition from viscous fingers to compact displacement during unstable drainage in porous media. Fulltekst i vitenarkiv
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Turquet, Antoine Leo; Flekkøy, Eirik Grude; Toussaint, Renaud & Jankov, Mihailo [Vis alle 7 forfattere av denne artikkelen] (2021). Complexity: “More is Different” also in porous media flows. Fulltekst i vitenarkiv
• Moura, Marcel; Måløy, Knut Jørgen; Jankov, Mihailo & Toussaint, Renaud (2013). Experimental study of a two-phase flow in a quasi-two-dimensional porous medium. Fulltekst i vitenarkiv
• Moura, Marcel; Måløy, Knut Jørgen; Jankov, Mihailo & Toussaint, Renaud (2012). Pressure-driven two-phase flow in a quasi-two-dimensional porous medium. Fulltekst i vitenarkiv
• Jankov, Mihailo (2010). Two phase flow in porous media with and without seismic stimulation. Universitetet i Oslo. Fulltekst i vitenarkiv

Se alle arbeider i NVA