The Experts below are selected from a list of 1875321 Experts worldwide ranked by ideXlab platform
Yuan Wang - One of the best experts on this subject based on the ideXlab platform.
-
a numerical manifold method model for analyzing fully coupled hydro mechanical processes in porous rock masses with discrete Fractures
Advances in Water Resources, 2017Co-Authors: Jonny Rutqvist, Mengsu Hu, Yuan WangAbstract:Abstract In this study, a numerical manifold method (NMM) model was developed for fully coupled analysis of hydro-mechanical (HM) processes in porous rock masses with discrete Fractures. Using an NMM two-cover-mesh system of mathematical and physical covers, Fractures are conveniently discretized by dividing the mathematical cover along Fracture traces to physical cover, resulting in a discontinuous model on a non-conforming mesh. In this model, discrete Fracture deformation (e.g. open and slip) and Fracture fluid flow within a permeable and deformable porous rock matrix are rigorously considered. For porous rock, direct pore-volume coupling was modeled based on an energy-work scheme. For mechanical analysis of Fractures, a Fracture constitutive model for mechanically open states was introduced. For fluid flow in Fractures, both along-Fracture and normal-to-Fracture fluid flow are modeled without introducing additional degrees of freedom. When the mechanical aperture of a Fracture is changing, its hydraulic aperture and hydraulic conductivity is updated. At the same time, under the effect of coupled deformation and fluid flow, the contact state may dynamically change, and the corresponding contact constraint is updated each time step. Therefore, indirect coupling is realized under stringent considerations of coupled HM effects and Fracture constitutive behavior transfer dynamically. To verify the new model, examples involving deformable porous media containing a single and two sets of Fractures were designed, showing good accuracy. Last, the model was applied to analyze coupled HM behavior of Fractured porous rock domains with complex Fracture networks under effects of loading and injection.
-
fully coupled hydro mechanical numerical manifold modeling of porous rock with dominant Fractures
Acta Geotechnica, 2017Co-Authors: Yuan Wang, Mengsu Hu, Jonny RutqvistAbstract:Coupled hydro-mechanical (HM) processes are significant in geological engineering such as oil and gas extraction, geothermal energy, nuclear waste disposal and for the safety assessment of dam foundations and rock slopes, where the geological media usually consist of Fractured rock masses. In this study, we developed a model for the analysis of coupled hydro-mechanical processes in porous rock containing dominant Fractures, by using the numerical manifold method (NMM). In the current model, the Fractures are regarded as different material domains from surrounding rock, i.e., finite-thickness Fracture zones as porous media. Compared with the rock matrix, these Fractured porous media are characterized with nonlinear behavior of hydraulic and mechanical properties, involving not only direct (poroelastic) coupling but also indirect (property change) coupling. By combining the potential energy associated with mechanical responses, fluid flow and solid–fluid interactions, a new formulation for direct HM coupling in porous media is established. For indirect coupling associated with Fracture opening/closure, we developed a new approach implicitly considering the nonlinear properties by directly assembling the corresponding strain energy. Compared with traditional methods with approximation of the nonlinear constitutive equations, this new formulation achieves a more accurate representation of the nonlinear behavior. We implemented the new model for coupled HM analysis in NMM, which has fixed mathematical grid and accurate integration, and developed a new computer code. We tested the code for direct coupling on two classical poroelastic problems with coarse mesh and compared the results with the analytical solutions, achieving excellent agreement, respectively. Finally, we tested for indirect coupling on models with a single dominant Fracture and obtained reasonable results. The current poroelastic NNM model with a continuous finite-thickness Fracture zone will be further developed considering thin Fractures in a discontinuous approach for a comprehensive model for HM analysis in Fractured porous rock masses.
Mengsu Hu - One of the best experts on this subject based on the ideXlab platform.
-
a numerical manifold method model for analyzing fully coupled hydro mechanical processes in porous rock masses with discrete Fractures
Advances in Water Resources, 2017Co-Authors: Jonny Rutqvist, Mengsu Hu, Yuan WangAbstract:Abstract In this study, a numerical manifold method (NMM) model was developed for fully coupled analysis of hydro-mechanical (HM) processes in porous rock masses with discrete Fractures. Using an NMM two-cover-mesh system of mathematical and physical covers, Fractures are conveniently discretized by dividing the mathematical cover along Fracture traces to physical cover, resulting in a discontinuous model on a non-conforming mesh. In this model, discrete Fracture deformation (e.g. open and slip) and Fracture fluid flow within a permeable and deformable porous rock matrix are rigorously considered. For porous rock, direct pore-volume coupling was modeled based on an energy-work scheme. For mechanical analysis of Fractures, a Fracture constitutive model for mechanically open states was introduced. For fluid flow in Fractures, both along-Fracture and normal-to-Fracture fluid flow are modeled without introducing additional degrees of freedom. When the mechanical aperture of a Fracture is changing, its hydraulic aperture and hydraulic conductivity is updated. At the same time, under the effect of coupled deformation and fluid flow, the contact state may dynamically change, and the corresponding contact constraint is updated each time step. Therefore, indirect coupling is realized under stringent considerations of coupled HM effects and Fracture constitutive behavior transfer dynamically. To verify the new model, examples involving deformable porous media containing a single and two sets of Fractures were designed, showing good accuracy. Last, the model was applied to analyze coupled HM behavior of Fractured porous rock domains with complex Fracture networks under effects of loading and injection.
-
fully coupled hydro mechanical numerical manifold modeling of porous rock with dominant Fractures
Acta Geotechnica, 2017Co-Authors: Yuan Wang, Mengsu Hu, Jonny RutqvistAbstract:Coupled hydro-mechanical (HM) processes are significant in geological engineering such as oil and gas extraction, geothermal energy, nuclear waste disposal and for the safety assessment of dam foundations and rock slopes, where the geological media usually consist of Fractured rock masses. In this study, we developed a model for the analysis of coupled hydro-mechanical processes in porous rock containing dominant Fractures, by using the numerical manifold method (NMM). In the current model, the Fractures are regarded as different material domains from surrounding rock, i.e., finite-thickness Fracture zones as porous media. Compared with the rock matrix, these Fractured porous media are characterized with nonlinear behavior of hydraulic and mechanical properties, involving not only direct (poroelastic) coupling but also indirect (property change) coupling. By combining the potential energy associated with mechanical responses, fluid flow and solid–fluid interactions, a new formulation for direct HM coupling in porous media is established. For indirect coupling associated with Fracture opening/closure, we developed a new approach implicitly considering the nonlinear properties by directly assembling the corresponding strain energy. Compared with traditional methods with approximation of the nonlinear constitutive equations, this new formulation achieves a more accurate representation of the nonlinear behavior. We implemented the new model for coupled HM analysis in NMM, which has fixed mathematical grid and accurate integration, and developed a new computer code. We tested the code for direct coupling on two classical poroelastic problems with coarse mesh and compared the results with the analytical solutions, achieving excellent agreement, respectively. Finally, we tested for indirect coupling on models with a single dominant Fracture and obtained reasonable results. The current poroelastic NNM model with a continuous finite-thickness Fracture zone will be further developed considering thin Fractures in a discontinuous approach for a comprehensive model for HM analysis in Fractured porous rock masses.
Jonny Rutqvist - One of the best experts on this subject based on the ideXlab platform.
-
a numerical manifold method model for analyzing fully coupled hydro mechanical processes in porous rock masses with discrete Fractures
Advances in Water Resources, 2017Co-Authors: Jonny Rutqvist, Mengsu Hu, Yuan WangAbstract:Abstract In this study, a numerical manifold method (NMM) model was developed for fully coupled analysis of hydro-mechanical (HM) processes in porous rock masses with discrete Fractures. Using an NMM two-cover-mesh system of mathematical and physical covers, Fractures are conveniently discretized by dividing the mathematical cover along Fracture traces to physical cover, resulting in a discontinuous model on a non-conforming mesh. In this model, discrete Fracture deformation (e.g. open and slip) and Fracture fluid flow within a permeable and deformable porous rock matrix are rigorously considered. For porous rock, direct pore-volume coupling was modeled based on an energy-work scheme. For mechanical analysis of Fractures, a Fracture constitutive model for mechanically open states was introduced. For fluid flow in Fractures, both along-Fracture and normal-to-Fracture fluid flow are modeled without introducing additional degrees of freedom. When the mechanical aperture of a Fracture is changing, its hydraulic aperture and hydraulic conductivity is updated. At the same time, under the effect of coupled deformation and fluid flow, the contact state may dynamically change, and the corresponding contact constraint is updated each time step. Therefore, indirect coupling is realized under stringent considerations of coupled HM effects and Fracture constitutive behavior transfer dynamically. To verify the new model, examples involving deformable porous media containing a single and two sets of Fractures were designed, showing good accuracy. Last, the model was applied to analyze coupled HM behavior of Fractured porous rock domains with complex Fracture networks under effects of loading and injection.
-
fully coupled hydro mechanical numerical manifold modeling of porous rock with dominant Fractures
Acta Geotechnica, 2017Co-Authors: Yuan Wang, Mengsu Hu, Jonny RutqvistAbstract:Coupled hydro-mechanical (HM) processes are significant in geological engineering such as oil and gas extraction, geothermal energy, nuclear waste disposal and for the safety assessment of dam foundations and rock slopes, where the geological media usually consist of Fractured rock masses. In this study, we developed a model for the analysis of coupled hydro-mechanical processes in porous rock containing dominant Fractures, by using the numerical manifold method (NMM). In the current model, the Fractures are regarded as different material domains from surrounding rock, i.e., finite-thickness Fracture zones as porous media. Compared with the rock matrix, these Fractured porous media are characterized with nonlinear behavior of hydraulic and mechanical properties, involving not only direct (poroelastic) coupling but also indirect (property change) coupling. By combining the potential energy associated with mechanical responses, fluid flow and solid–fluid interactions, a new formulation for direct HM coupling in porous media is established. For indirect coupling associated with Fracture opening/closure, we developed a new approach implicitly considering the nonlinear properties by directly assembling the corresponding strain energy. Compared with traditional methods with approximation of the nonlinear constitutive equations, this new formulation achieves a more accurate representation of the nonlinear behavior. We implemented the new model for coupled HM analysis in NMM, which has fixed mathematical grid and accurate integration, and developed a new computer code. We tested the code for direct coupling on two classical poroelastic problems with coarse mesh and compared the results with the analytical solutions, achieving excellent agreement, respectively. Finally, we tested for indirect coupling on models with a single dominant Fracture and obtained reasonable results. The current poroelastic NNM model with a continuous finite-thickness Fracture zone will be further developed considering thin Fractures in a discontinuous approach for a comprehensive model for HM analysis in Fractured porous rock masses.
Huidong Wang - One of the best experts on this subject based on the ideXlab platform.
-
heat extraction mechanism in a geothermal reservoir with rough walled Fracture networks
International Journal of Heat and Mass Transfer, 2018Co-Authors: Yun Chen, Huidong WangAbstract:Abstract This study aims at understanding the mechanism of heat extraction from a geothermal reservoir characterized by rough-walled Fracture networks. A unified pipe-network method (UPM) which simplifies both Fractures and the rock matrix as pipes is developed considering the local thermal non-equilibrium (LTNE) theory, and it is verified against an analytical solution. Three-dimensional simulations of macroscopic fluid flow and heat transfer in a Fractured geothermal reservoir are conducted to take account of Fracture roughness. The channeling effect and the heterogeneous distribution of fluid temperature in a core-scale model with a rough-walled Fracture surface are simulated. An equivalent heat transfer coefficient (EHTC) is obtained from numerical experiments with respect to the flow rate, mechanical aperture and the equivalent hydraulic aperture. A representative element volume is then used to investigate the flow and heat transfer process in a geothermal reservoir with rough-walled Fracture networks by applying the obtained EHTC. Results demonstrate that it is essential to use the proposed EHTC since the constant heat transfer coefficient (HTC) recommended in previous studies underestimates the final outlet fluid temperature in cases with rough-walled Fractures.
Christoph Clauser - One of the best experts on this subject based on the ideXlab platform.
-
numerical simulation of flow and heat transfer in Fractured crystalline rocks application to the hot dry rock site in rosemanowes u k
Geothermics, 1998Co-Authors: Olaf Kolditz, Christoph ClauserAbstract:Abstract This study examines heat transfer during forced water circulation through Fractured crystalline rock using a fully 3-D finite-element model. We propose an alternative to strongly simplified single or multiple parallel Fracture models or porous media equivalents on the one hand, and to structurally complex stochastic Fracture network models on the other hand. The applicability of this “deterministic Fracture network approach” is demonstrated in an analysis of the 900-day circulation test for the Hot Dry Rock (HDR) site at Rosemanowes (U.K.). The model design with respect to structure, hydraulic and thermal behavior is strictly conditioned by measured data such as Fracture network geometry, hydraulic and thermal boundary and initial conditions, hydraulic reservoir impedance, and thermal drawdown. Another novel feature of this model is that flow and heat transport in the Fractured medium are simulated in a truly 3-D system of fully coupled discrete Fractures and porous matrix. While an optimum model fit is not the prime target of this study, this approach permits one to make realistic long-term predictions of the thermal performance of HDR systems.
