ORCID Profile
0000-0001-9834-3084
Current Organisation
University of Stuttgart
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: CRC Press
Date: 04-09-2014
DOI: 10.1201/B17435-253
Publisher: Wiley
Date: 2021
Abstract: In the community of porous and fractured geomaterials properties regarding underground fluid storage and matter are of high interest. Investigations on fluid‐filled fractures require strong hydro mechanical coupling of fracture and porous domain to reproduce deformation triggered, non‐local phenomena such as the Noordbergum effect. Special numerical treatment is necessary to solve the tightly coupled system consisting of high aspect ratio fractures and a surrounding porous matrix, since other approaches such as Direct Numerical Simulations fail due to technical issues (number of Degrees of Freedom (DoF)). Once heterogeneous initial aperture distributions are of interest coarse grained continuum approaches (Biot's poroelasticity theory) facing technical limitations since explicit meshing of the fracture geometry is required. This work uses hybrid‐dimensional interface elements in a fully coupled implicit formulation to investigate its capacities regarding heterogeneous fracture surfaces in three dimensions.
Publisher: Springer Science and Business Media LLC
Date: 10-02-2019
Publisher: Springer Science and Business Media LLC
Date: 20-01-2022
DOI: 10.1007/S10596-021-10120-8
Abstract: We introduce a partitioned coupling approach for iterative coupling of flow processes in deformable fractures embedded in a poro-elastic medium that is enhanced by interface quasi-Newton (IQN) methods. In this scope, a unique computational decomposition into a fracture flow and a poro-elastic domain is developed, where communication and numerical coupling of the in idual solvers are realized by consulting the open-source library preCICE. The underlying physical problem is introduced by a brief derivation of the governing equations and interface conditions of fracture flow and poro-elastic domain followed by a detailed discussion of the partitioned coupling scheme. We evaluate the proposed implementation and undertake a convergence study to compare a classical interface quasi-Newton inverse least-squares (IQN-ILS) with the more advanced interface quasi-Newton inverse multi-vector Jacobian (IQN-IMVJ) method. These coupling approaches are verified for an academic test case before the generality of the proposed strategy is demonstrated by simulations of two complex fracture networks. In contrast to the development of specific solvers, we promote the simplicity and computational efficiency of the proposed partitioned coupling approach using preCICE and FEniCS for parallel computations of hydro-mechanical processes in complex, three-dimensional fracture networks.
Publisher: Trans Tech Publications, Ltd.
Date: 07-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.846.391
Abstract: The computational treatment of discontinuities within the framework of the finite element method (FEM) is a requirement for simulations of fracturing of solids and has become a challenging topic in computational mechanics. Particularly popular amongst the advanced schemes is the extended finite element method (XFEM) which is based on enrichment of shape functions and falls within the framework of the partition of unity method. Because there is no simple way to track the interface of discontinuities, the computer implementation of the XFEM is not as straightforward as the FEM. One method to solve the interface tracking problem is the level set method (LSM) which introduces another partial differential equation. The level set equation describes the change of an interface due to a known velocity field. To obtain its solution, the FEM can also be employed. This contribution investigates the XFEM-LSM technique with element enrichment and the integration of discontinuous elements for the modelling of cracks or material interfaces. Numerical experiments illustrate the capabilities and accuracy of the resulting formulation.
Publisher: Wiley
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 30-07-2021
DOI: 10.1007/S12665-021-09767-4
Abstract: We applied a hybrid-dimensional flow model to pressure transients recorded during pumping experiments conducted at the Reiche Zeche underground research laboratory to study the opening behavior of fractures due to fluid injection. Two distinct types of pressure responses to flow-rate steps were identified that represent radial-symmetric and plane-axisymmetric flow regimes from a conventional pressure-diffusion perspective. We numerically modeled both using a radial-symmetric flow formulation for a fracture that comprises a non-linear constitutive relation for the contact mechanics governing reversible fracture surface interaction. The two types of pressure response can be modeled equally well. A sensitivity study revealed a positive correlation between fracture length and normal fracture stiffness that yield a match between field observations and numerical results. Decomposition of the acting normal stresses into stresses associated with the deformation state of the global fracture geometry and with the local contacts indicates that geometrically induced stresses contribute the more the lower the total effective normal stress and the shorter the fracture. Separating the contributions of the local contact mechanics and the overall fracture geometry to fracture normal stiffness indicates that the geometrical stiffness constitutes a lower bound for total stiffness its relevance increases with decreasing fracture length. Our study demonstrates that non-linear hydro-mechanical coupling can lead to vastly different hydraulic responses and thus provides an alternative to conventional pressure-diffusion analysis that requires changes in flow regime to cover the full range of observations.
Publisher: Oxford University Press (OUP)
Date: 28-08-2021
DOI: 10.1093/GJI/GGAB354
Abstract: In this work, we propose a hydro-mechanical simulation model to study the strong interaction of fluid flow and fracture deformation under in situ stress conditions. The general model is reduced under physics-based assumptions to provide an efficient numerical approach for inverse analysis of experimental studies and is applied to experimental field data obtained from hydraulic tests conducted at the Grimsel Test Site, Switzerland. The present set of hydro-mechanical measurement data provides not only valuable information about the transient pressure and flow evolution but also the transient change of fracture deformation. We aim to introduce a strongly coupled hydro-mechanical model to numerically characterize the fractured reservoir based on experimental data below the limit of hydraulically induced irreversible changes of the reservoir’s properties. Insights into the leading mechanisms of flow processes throughout hydraulic testing under in situ conditions are then gained by best numerical fits of the measurement data. Based on the experimental and numerical findings, this study emphasizes the importance of a consistent consideration of local and non-local fracture deformation throughout inverse analysis of hydraulic testing data to (a) better understand hydro-mechanical flow processes in fractured reservoirs and (b) increase the estimation quality of hydraulic properties of tested fractures.
No related grants have been discovered for Patrick Schmidt.