Papers by Torstein Jøssang
Random Fluctuations and Pattern Growth: Experiments and Models, 1988
Growth models and viscous fingers are studied on simple percolation models of porous media. Studi... more Growth models and viscous fingers are studied on simple percolation models of porous media. Studies include computer and real experiments on square lattice models, at the percolation threshold, and exact calculations of deterministic flow on non-random fractal models. Crossover away from the threshold is also analyzed, using both computer simulations and scaling theory.
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Springer eBooks, 2001
Branched patterns are common in geological systems. Perhaps the most ubiquitous example is dendri... more Branched patterns are common in geological systems. Perhaps the most ubiquitous example is dendritic patterns formed by the growth of mineral crystals under far-from-equilibrium conditions, and the most familiar example is branched drainage networks (and the associated drainage divide networks). The growth of minerals leads to a wide variety of branched (and unbranched) patterns, because of the wide range of mineral compositions, growth conditions and growth rates. Branched patterns can also be formed by a variety of other processes such as the dissolution or melting of porous materials by fluids that are injected into them, fracture processes and fluid-fluid displacement processes at high capillary numbers. Aggregates composed of small particles may also form extensively branched structures, and structures of this type are widespread in rivers, lakes, marine environments, and in planetary atmospheres [1]. Marine snow [2–4] formed from a variety of materials including living and dead organisms (such as bacteria and diatoms) fecal pellets, polysaccharides and inorganic particles is an important example. Other examples include micrometeorites [5] and aggregates formed in river estuaries from clay and other mineral particles, which are transported in great quantities by rivers. This important class of branched structures will not be discussed further in this review.
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Biochemical Society Transactions, Apr 1, 1981
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Wave Motion, 2017
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Scattering Techniques Applied to Supramolecular and Nonequilibrium Systems, 1981
The thermal stability of immunoglobins is a critical parameter both to experimental immunologists... more The thermal stability of immunoglobins is a critical parameter both to experimental immunologists and clinicians responsible for administration of antibody preparations. In diagnostic immunology heating of serum at 56C for 30 minutes has become a well established method of inactivating complement in immunological assays. This procedure usually does not influence the antibody activity or the other main biological properties of the immunoglobins. In contrast, heating of IgG at 63°C for 30 minutes is a widely used method to produce soluble IgG aggregates. Such aggregates possess many biological properties which make them suitable for use as controls in studies concerning soluble antigen-antibody complexes. 1,2 The structure of the heat aggregates and the mechanism by which they are formed has been studied by several methods. For the analysis of the hydrodynamic properties, ultracentrifugation and &elfiltration have been the most used techniques,3,4,5 and for the study of the biological properties of the soluble aggregates, complement fixation methods has been shown to be very sensitive.6 By dynamic light scattering we measure the diffusion coefficients of the components in a solution of IgG. In this way we can follow the process of aggregation under different conditions.
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Physical Review E, 1999
Water beneath a layer of oil in a producing reservoir may rise and form a bell-shaped cone in the... more Water beneath a layer of oil in a producing reservoir may rise and form a bell-shaped cone in the vicinity of the well. We discuss how the dynamics of cone formation in two dimensions depends on the gravitational contrast, the interfacial tension, and the flow rate of oil. For a constant flow rate below a critical rate Q(c), stable cones are formed. At rates above Q(c), two dynamical regimes are expected. These are slow initial formation and fast breakthrough to the well. Quasi-two-dimensional transparent porous models were used to perform cone formation experiments. Effective acceleration due to gravity was systematically varied. The experiments were simulated using a stochastic model based on invasion percolation in which capillary forces were explicitly taken into account. We find agreement between experiments and simulations, and consistency with the theoretical predictions.
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Physical Review E, 2003
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Physical Review A, 1987
A gas displacing a high-viscosity liquid in a porous medium generates a fractal finger structure ... more A gas displacing a high-viscosity liquid in a porous medium generates a fractal finger structure similar to that obtained in diffusion-limited aggregation (DLA). This structure is controlled by the surface dynamics of the growing active zone. The dynamics of viscous fingering in a two-dimensional porous model has been investigated. We have studied the radius of the active zone and the
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Physical Review Letters, 1996
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Physical Review Letters, 1992
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Physical Review Letters, 1988
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Physical Review Letters, 1998
Air injected into a two-dimensional porous medium displaced a flowing defending fluid. At low flo... more Air injected into a two-dimensional porous medium displaced a flowing defending fluid. At low flow rates the invading air formed chains of fractal clusters similar to those observed in gradient percolation. The defending fluid was excluded from the invading region and moved around the invading clusters. Above a critical flow rate the invaded region fragmented into a plumelike structure that
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Physica A: Statistical Mechanics and its Applications, 1991
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Physica A: Statistical Mechanics and its Applications, 1991
A real space renormalization group algorithm is used to evaluate macroscopic permeabilities. The ... more A real space renormalization group algorithm is used to evaluate macroscopic permeabilities. The algorithm was tested on many different distributions, with large spatial correlations and anisotropies, and the results are very close to the expected exact values.
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Physica A: Statistical Mechanics and its Applications, 1992
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Nature, 1996
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Marine and Petroleum Geology, 2000
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Journal of Statistical Physics, 1986
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Journal of Geophysical Research: Solid Earth, 1999
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Papers by Torstein Jøssang