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Shear strain localization refers to the phenomenon of accumulation of material deformation in narrow slip zones. Many materials exhibit strain localization under different spatial and temporal scales, particularly rocks, metals, soils, and concrete. In the Earth's crust, irreversible deformation can occur in brittle as well as in ductile regimes. Modeling of shear zones is essential in the geodynamic framework. Numerical modeling of strain localization remains challenging due to the non‐linearity and multi‐scale nature of the problem. We develop a numerical approach based on graphical processing units (GPU) to resolve the strain localization in two and three dimensions of a (visco)‐hypoelastic‐perfectly plastic medium. Our approach allows modeling both the compressible and incompressible visco‐elasto‐plastic flows. In contrast to symmetric shear bands frequently observed in the literature, we demonstrate that using sufficiently small strain or strain rate increments, a non‐symmetric strain localization pattern is resolved in two‐ and three‐dimensions, highlighting the importance of high spatial and temporal resolution. We show that elasto‐plastic and visco‐plastic models yield similar strain localization patterns for material properties relevant to applications in geodynamics. We achieve fast computations using three‐dimensional high‐resolution models involving more than 1.3 billion degrees of freedom. We propose a new physics‐based approach explaining spontaneous stress drops in a deforming medium. Plain Language Summary: Strain localization is the accumulation of strain in narrow regions of rocks and other materials like metals, soils, and concrete, occurring at different scales. The strength of most geomaterials, particularly rocks, is strongly pressure‐dependent, with strength increasing with increasing pressure. We developed efficient numerical algorithms using High‐Performance Computing (HPC) and graphical processing units (GPUs) to model strain localization in 2D and 3D for applications in geodynamics and earthquake physics. Unlike previous models, our method reveals non‐symmetrical patterns by using very small strain increments, highlighting the need for high‐detail modeling. We found that elasto‐plastic and visco‐plastic models show similar strain patterns for relevant materials. Our method also achieves fast, detailed computations with over 1.3 billion variables and offers a new explanation for sudden stress drops in deforming materials. Key Points: We resolve material instability during deformation resulting in a non‐symmetric pattern of strain localizationWe demonstrate the similarity in patterns of strain localization between frictional and time‐dependent plasticity modelsWe achieve fast numerical simulations in high‐resolution model setups in three dimensions involving more than 500 million degrees of freedom [ABSTRACT FROM AUTHOR]

We present a recent development of the MUFITS reservoir simulator aiming at modelling the transport of fluids whose properties and phase equilibria are calculated in a user-supplied external shared library. Both the explicit correlations and tabulated data for the fluid parameters can be implemented in the library that we name the EoS-module (Equation of State-module). An iterative approach—which, for example, is based on the phase equilibria calculation through the Gibbs energy minimisation (GEM) method, can also be used in the EoS-module. A considerable effort has been undertaken to minimise the number of program procedures exported by the shared library. This should facilitate and ease the usage of the developed software extension by the scientific community. Furthermore, we supplement the article with the source code of two simple EoS-modules that can serve as templates in other modelling and software development efforts. The EoS-modules are also useful for coupling MUFITS with other elaborate software for fluid property prediction. To demonstrate such a possibility, we supplement the article with the source code of a more complicated EoS-module that couples MUFITS with the geochemical code GEMS3K. This module is used in a simple 1-D benchmark study showing the capabilities of MUFITS for modelling reactive transport in porous media. [ABSTRACT FROM AUTHOR]

We present a mathematical model of nonreactive fluid flow in a compacting porous medium. The model differs from previous formulations by considering fluid transport in the frame of reference moving with the solid phase. Such an approach guarantees material balance for the fluid and solid phases not only in the small‐porosity limit but also for large values of porosity. Using the numerical implementation of the proposed model, we simulate magmatic fluid transport in the Earth's upper crust. We account for the thermal softening of rocks, the plastic deformation of the solid matrix through decompaction weakening, and realistic fluid properties in a wide range of depths, including those above and below the brittle‐ductile transition (BDT). We show that our simulation approach can resolve the localized flow in the ductile zone and numerous hydrothermal convection cells in the brittle zone. We investigate the influence of decompaction weakening on high‐porosity channels forming in the ductile zone and their interaction with the convection in the brittle zone. We show that compaction causes magmatic fluid focusing and accumulation in high‐porosity lenses beneath the low‐porosity BDT zone. We show that magmatic fluid transfer through the BDT occurs mainly through the roofs of the lenses, which results in a plume of hydrothermal convection always sitting atop every lens. Other plumes between the lenses are associated with the convection of meteoric water that transfers only heat from the BDT to the surface. The simulations indicate that the lenses can be tracked by measuring certain parameters at the surface. Plain Language Summary: Magma cooling and degassing cause large volumes of hot water to exsolve. We investigate the flow of this magmatic fluid to the Earth's surface through permeable rocks. We account for complicated deformations of rocks and associated pore space closing and opening, that is, compaction and decompaction, which causes a spontaneous channelization of the flow at large depths. These channels interact with the meteoric water convection in the Earth's uppermost crust. We simulate this interaction and show that the magmatic fluid focuses and accumulates in high‐porosity lenses at a shallow depth. Most of the fluid flows through these lenses and escapes to the surface through their roofs. Thus, the lenses can be associated with regions of ore deposit formation. Above the lenses, the magmatic fluid mixes with the meteoric water, causing a convective plume of ascending water to sit above each lens. Therefore, the magmatic fluid reaches the surface in narrow areas that can be associated with hot springs. Key Points: We simulate magmatic fluid transport above, below, and through the brittle‐ductile transition (BDT)Interaction with meteoric convection causes fluid focusing below the BDT in high‐porosity lensesMagmatic fluid transport through BDT occurs mainly through the roofs of the lenses [ABSTRACT FROM AUTHOR]