Acta Geotechnica - A concise, two-dimensional discrete heat transfer model is presented, which considers the thermal resistance effects of cracks. The discrete heat transfer model discretizes the... 相似文献
A novel two-dimensional mixed fracture–pore seepage model for fluid flow in fractured porous media is presented based on the computational framework of finite-discrete element method (FDEM). The model consists of a porous seepage model in triangular elements bonded by unbroken joint elements, as well as a fracture seepage model in broken joint elements. The principle for determining the fluid exchange coefficient of the unbroken joint element is provided to ensure numerical accuracy and efficiency. The mixed fracture–pore seepage model provides a simple but effective tool for solving fluid flow in fractured porous media. In this paper, examples of 1D and 2D seepage flow in porous media and porous media with a single fracture or multiple fractures are studied. The simulation results of the model match well with theoretical solutions or results obtained by commercial software, which verifies the correctness of the mixed fracture–pore seepage model. Furthermore, combining FDEM mechanical calculation and the mixed fracture–pore seepage model, a coupled hydromechanical model is built to simulate fluid-driven dynamic propagation of cracks in the porous media, as well as its influence on pore seepage and fracture seepage.
Based on the combined finite-discrete element method (FDEM), a two-dimensional coupled hydro-thermal model is proposed. This model can simulate fluid flow and heat transfer in rock masses with arbitrary complex fracture networks. The model consists of three parts: a heat conduction model of the rock matrix, a heat-transfer model of the fluid in the fracture (including the heat conduction and convection of fluid), and a heat exchange model between the fluid and rock at the fracture surface. Three examples with analytical solutions are given to verify the correctness of the coupled model. Finally, the coupled model is applied to hydro-thermal coupling simulations of a rock mass with a fracture network. The temperature field evolution, the effect of thermal conductivity of the rock matrix thermal conductivity and the fracture aperture on the outlet temperature are studied. The coupled model presented in this paper will enable the application of FDEM to study rock rupture driven by the effect of hydro-thermo-mechanical coupling in geomaterials such as in geothermal systems, petroleum engineering, environmental engineering and nuclear waste geological storage.
A simple three-dimensional heat transfer model is developed to consider the hindering effect of cracks on heat transfer. The 3D heat transfer model can also be applied to numerical methods such as the combined finite-discrete element method (FDEM), discrete element method (DEM), discontinuous deformation analysis (DDA), the numerical manifold method (NMM), and the finite element method (FEM) to construct thermo-mechanical coupling models that allow these methods to solve thermal cracking problems and dynamically consider the hindering effect of cracks on heat transfer. In the 3D heat transfer model, the continuous-discontinuous medium is discretized into independent tetrahedral elements, and joint elements are inserted between adjacent tetrahedral elements. Heat transfer calculations for continuous-discontinuous media are converted to heat conduction in tetrahedral elements and the heat exchange between the adjacent tetrahedral elements through the joint element. If the joint element between adjacent tetrahedral elements breaks (ie, a crack generates), the heat exchange coefficient of the joint element is reduced to account for the hindering effect of cracks on heat conduction. Then the model and the FDEM are combined to build a thermo-mechanical coupling model to simulate thermal cracking. The thermally induced deformation, stress, and cracking are investigated by the thermo-mechanical coupling model, and the numerical results are compared with analytical solutions or experimental results. The 3D heat transfer model and thermo-mechanical model can provide a powerful tool for simulating heat transfer and thermal cracking in a continuous-discontinuous medium. 相似文献
This paper proposes a three-dimensional coupled hydrothermal model for fractured rock based on the finite-discrete element method to simulate fluid flow and heat transport. The 3D coupled hydrothermal model is composed of three main parts: a heat conduction model for the rock matrix, a heat transfer model for the fluid in the fractures (including heat conduction and heat convection), and a heat exchange model between the rock matrix and the fluid in the fractures. Four examples with analytical solutions are provided to verify the model. A heat exchange experiment of circulating water in a cylindrical granite sample with one fracture is simulated. The simulation results agree well with the experimental results. The effects of the fracture aperture, fluid viscosity, and pressure difference on the heat exchange between the fluid and rock are studied. Finally, an application concerned with heat transport and fluid flow in fractured rock is presented. The simulation results indicate that the 3D fully coupled hydrothermal model can capture the fluid flow and temperature evolution of rocks and fluids. 相似文献