Castro-Orgaz, OscarGiraldez, Juan, VHager, Willi H.Cantero-Chinchilla, Francisco N....
1.1-1.20页查看更多>>摘要：Overland flow resulting from the rainfall-runoff transformation is an important hydrological process in agricultural and urban watersheds, occurring in the form of a thin fluid sheet moving on rough and relatively steep terrain. Mixed flows involving moving critical points are frequent, especially in urban drainage, but a method to deal with these flows is so far not available. In this work a new and robust solution method for the computation of equilibrium mixed flows is presented, resulting in solutions not available so far. Based on these results, the convergence features to mixed flows of a dynamic wave model developed are investigated choosing suitable tailwater boundary conditions. The new solution method developed for mixed flows reveals that pseudo-uniform flow profiles are closer to dynamic wave profiles than kinematic profiles. It allowed the definition of a new kinematic-wave truncation of the momentum equation, the pseudo-kinematic wave, suitable for unsteady rainfall-runoff modeling. The new shallow water wave approach proposed is closer to dynamic waves than the standard kinematic approach and permits to simulate unsteady overland flows more accurately over a wider range of conditions, e.g. for kF(0)(2) > 5 and F-0 < 2. The dynamic wave model presented is compared with experiments, other computational solutions, and two new analytical solutions developed, one for steady flows and another for unsteady flows. The steady mixed flow profiles are compared with experiments and results of the dynamic wave model, detailing the formation of critical points. Dynamic, kinematic and pseudo-kinematic waves are extensively compared for flow conditions where the kinematic wave is invalid. Finally, the roll wave development, which is not detailed so far in overland flow under rainfall, is considered to settle an upper validity limit of the new pseudo-kinematic wave approach.
Kang, JinzhengShi, XiaoqingMo, ShaoxingSun, Alexander Y....
1.1-1.17页查看更多>>摘要：The secure implementation of geological carbon sequestration (GCS) critically hinges on accurately localization of CO2 leakage through inverse modeling of plume migration dynamics in heterogeneous reservoirs. This process is inherently challenged by subsurface uncertainties and the complexity of multiphase flow. Advances in various deep-learning-based surrogate models have been made to improve computational efficiency. Especially, PhysicsInformed Neural Networks (PINNs) have gained widespread application due to their integration of the partial differential equation (PDE) into the loss function. However, conventional PINNs still face critical limitations in handling two-phase flow dynamics and high-dimensional parameter spaces due to the discretization requirements of PDE. To address these challenges, we propose a Physics-Aware Convolutional LSTM (PA-CLSTM) surrogate model that intrinsically embeds flow gradient information into the ConvLSTM architecture. Unlike PINNs which require PDE discretization as part of the loss function, PA-CLSTM encodes physical constraints through Sobel operator-derived velocity fields in latent space, thereby avoiding the need for PDE discretization, while maintaining compatibility with spatiotemporal feature extraction. Validation with a synthetic 2D saline aquifer demonstrate, PA-CLSTM achieves a five-fold acceleration over numerical simulations (TOUGH2-ECO2N) and a 67% reduction of inversion RMSE (from 1.65 to 0.59) of estimated permeability field in the focused area, compared to purely data-driven ConvLSTM. Meanwhile, PA-CLSTM inversion results accurately localize the CO2 leakage. Compared to the ConvLSTM, the leakage location estimation RMSE decreased from 7.44 to 1.09, approaching the numerical simulation result of 0.68. In this work, we introduce the PA-CLSTM model in GCS, which significantly improves the inversion speed compared to numerical simulation and enhances accuracy compared to another surrogate model ConvLSTM.
Sin, SotheavuthNasir, MuhammadWang, KailinPatmonoaji, Anindityo...
1.1-1.15页查看更多>>摘要：Understanding of particle migration by fluid-particle interactions in immiscible two-phase flow systems in porous media is crucial for subsurface applications. However, pore-scale investigations of particle migration in immiscible two-phase flow systems remain limited for three-dimensional (3D) porous media because of the complexities of fluid flow in such media. Here, we employed microfocus X-ray computed tomography (CT) to investigate the effects of interfacial tension and viscous force on particle migration during fluid-particle interactions in strong drainage and imbibition for the pore-scale process. A mixture of two differently sized particles was used as a 3D heterogeneous porous medium. The experimental conditions cover the logarithmic values of the capillary number (LogCa) range between-7.476 and-4.777 and of a fixed viscosity ratio (LogM) of-0.867, which are used to simulate the carbon dioxide (CO2) sequestration. The results show that particle migration significantly proceeded throughout the medium for strong drainage compared to strong imbibition. At a low injection flow rate or LogCa, interfacial tension strongly influenced particle accumulation, altering pore networks. The combined effects of interfacial tension and viscous force enhanced particle migration with an increase in LogCa. In strong drainage, the particles migrated with the interface expansion between the two phases. However, in strong imbibition, they were displaced along with the fluid flow because of the presence of film formations. The findings of this study improve the understanding of particle migration by fluid-particle interactions under different injection flow rates and wettability conditions in 3D heterogeneous porous media.
Bui, Cuong MaiMatthai, Stephan K.
1.1-1.17页查看更多>>摘要：In complex fracture networks, dynamic fluid-flow patterns arise already at flow velocities in the centimetre-per-second (cm/s) range. Yet, these phenomena get ignored or underestimated when such flows are modelled using Stokes' equation or the steady-state Darcy's law approximations of the Navier-Stokes equation (NSE). Here we apply Detached-Eddy Simulation to solve the NSE in interconnected rock fractures, carrying out an investigation of transient flow phenomena. Our field-data-based numerical simulation-derived results reveal that fracture flow becomes unsteady at cm/s velocities. Dynamic eddies emerge across several length scales, increasing the tortuosity of the flow and altering the fluid distribution in fracture branches. Pressure fluctuations are detectable at the network scale, reaching magnitudes of similar to 10% of the total pressure drop. The contribution of inertial losses to the hydraulic head gradient across the network increases substantially with the onset of non-stationary eddies, confirming that they are the primary source of flow nonlinearity.
Roknian, Arash AndreaScotti, AnnaFumagalli, Alessio
1.1-1.18页查看更多>>摘要：The objective of this study is to better understand the influence of fractures on the possibility of free convection in porous media. Fractures are ubiquitous in porous media and criteria based on upscaled permeability are known to fail for fractured porous media. To this aim, we introduce a novel method for the assessment of convective stability through the eigenvalue analysis of the linearized numerical problem instead of solving the problem in time until a steady state is reached. The new method is shown to be in agreement with existing literature cases both in simple and complex fracture configurations. With respect to direct simulation in time, the results of the eigenvalue method lack information about the strength of convection and the steady state solution, they however provide detailed (quantitative) information about the behavior of the solution near the initial equilibrium condition. Furthermore, not having to solve a time-dependent problem makes the method computationally very efficient. The results of this work allow us to determine the dominant convective modes in 2D and 3D and to shed light on the role of the porous matrix in convective circuits.
Pujol, LeoChen, ShangzhiGarambois, Pierre-Andre
1.1-1.15页查看更多>>摘要：This contribution presents a gradient-based inverse modeling approach for the inference of distributed infiltration parameters in a 2D shallow water hydraulic model. It describes the implementation of rain and infiltration mass source terms in the DassFlow direct-inverse modeling platform and their validation against experimental data. Synthetic experiments are used to showcase the complexity of the inverse problems posed by the inference of infiltration parameters through hydraulic signature analysis, stochastic parameter space exploration and inverse modeling with distributed or multi-variate controls. To address spatial uncertainty in the context of sparse observations, spatial constraints are imposed to sought infiltration parameters in the form of homogeneous areas, or patches, sharing the resolution of available soil maps. They are also introduced in the form of a parameter model based on pedotransfer functions, which are used to reduce the dimensionality of the inverse problem and impose spatial coherence to the inferred distributed parameters. This upgrade of the direct model enables integrating a priori knowledge of parameter distribution carried by physical descriptor maps into the assimilation process, hence providing a spatially regularizing effect. Inference results for a fully distributed parametrization without regularization, which is achieved by solving of a high-dimensional inverse problem, are also presented. The methodology is applied to real catchments within the R & eacute;al Collobrier hydrological observatory in southeastern France, monitored by INRAE. In a model containing high-resolution topography and rain data, real downstream discharge observations are assimilated to infer distributed infiltration parameters maps, including through regionalized pedotransfer functions. This leads to the inference of effective infiltration model parameters that provide a better fit to real flow observations.
Sharma, Kunwar MrityunjaiTsang, Chin-FuGeier, JoelPensado, Osvaldo...
1.1-1.14页查看更多>>摘要：Discrete Fracture Network (DFN) models for evaluating flow and transport in low-permeability fractured rocks are important tools in safety assessments of nuclear waste repositories, and also important for other geoengineering and environmental applications. The well-known phenomena of flow channeling, arising from both intra-fracture and inter-fracture heterogeneities, is in general difficult to implement in these models. The present study uses the Channel Network Model (CNM) concept as a complementary approach to DFN models, with focus on channelized flow within fracture planes and in the fracture network. A method used to generate CNMs based on channels connecting centroids of fracture planes was implemented within a pychan3d library and applied to a 3D DFN model based on field data from Forsmark, Sweden. Three sets of realizations of the channel network are used to characterize the flow and transport system between deformation zones in the granitic host rock. The results indicate the significance of very low-conductivity fractures in providing critical flow connections in these rocks. It is shown that only a few (4 to 6 in our cases) key flow bridges within a network of 9000 or more fractures control its flow and transport. The use of CNMs together with DFN models enhances confidence in safety assessments for nuclear waste repositories and other applications, while providing valuable insights into complex flow and transport behavior in low-fracture-permeability rocks.
Guo, JiafanWang, ZhechaoQiao, LipingFeng, Hao...
1.1-1.15页查看更多>>摘要：When two fluids flow simultaneously in a porous medium at a low flow rate, known as steady-state two-phase flow, the total pressure drop deviates from a linear relationship with the Darcy flux. This deviation is primarily caused by the capillary pressure drop induced by interphase interference at pore throats. This study aims to estimate the capillary pressure drop based on fluid-fluid interfacial area at the pore scale. Recognizing that steady-state two phase flow typically exhibits discontinuous behavior, we proposed a simple equation to explain the relationship between total pressure drop, viscous pressure drop, and capillary pressure drop. Experiments were conducted in transparent micromodels to investigate the effects of flow rate, average viscosity and pore structure under both drainage and imbibition conditions. The results indicate a linear relationship between capillary pressure drop and the specific interfacial area of the moving wetting and moving non-wetting phase. Additionally, the slope of the capillary pressure drop-specific interfacial area curve is only related to the flow rate. Moreover, we established and verified the relationship between the specific interfacial area and relative permeability. This study provides new insights into the nonlinear relationship between Darcy flux and pressure drop in two-phase flow.
Ye, QiangHuang, ZijieZheng, QiangZeng, Lingzao...
1.1-1.16页查看更多>>摘要：Accurate modeling of soil water movement in the unsaturated zone is essential for effective soil and water resources management. Physics-informed neural networks (PINNs) offer promising potential for this purpose, but necessitate retraining upon changes in initial or boundary conditions, posing a challenge when adapting to variable natural conditions. To address this issue, inspired by the operator learning with more universal applicability than function learning, we develop a physics-informed deep operator network (PI-DeepONet), integrating physical principles and observed data, to simulate soil water movement under variable boundary conditions. In the numerical case, PI-DeepONet achieves the best performance among three modeling strategies when predicting soil moisture dynamics across different testing areas, especially for the extrapolation one. Guided by both data and physical mechanisms, PI-DeepONet demonstrates greater accuracy than HYDRUS in capturing spatio-temporal moisture variations in real-world scenario. Furthermore, PI-DeepONet successfully infers constitutive relationships and reconstructs missing boundary flux condition from limited data by incorporating known prior physical information, providing a unified solution for both forward and inverse problems. This study is the first to develop a PI-DeepONet specifically for modeling real-world soil water movement, highlighting its potential to improve predictive accuracy and reliability in vadose zone modeling by combining data-driven approaches with physical principles.
Sun, JiazhiShi, WenlongJing, MiaoLu, Chunhui...
1.1-1.12页查看更多>>摘要：Horizontal less permeable barriers have been proposed as a viable approach for reducing seawater intrusion in coastal aquifers. However, the performance of such barriers on enhancing coastal well pumping remains unclear. This study presents an analytical model based on the potential theory capable of evaluating the effect of a horizontal less permeable barrier on the maximum sustainable withdrawal rate in a finite-domain coastal aquifer. The model contains a steady-state groundwater flow equation that includes a Dirac delta function representing the pumping well, a constant-head coastline boundary, a constant-flux inland boundary and no-flux lateral boundary conditions. A localized equivalent hydraulic conductivity is applied exclusively within the barrier region and its adjacent aquifer interface zone. The solution is derived using the finite Fourier Cosine transform. Numerical simulations employing the variable-density flow code SEAWAT are conducted to validate the proposed analytical solution, and the analytical results align well with the numerical simulation results. The sensitivity analysis based on the analytical solution and dimensionless parameters reveals that the maximum sustainable withdrawal rate can be up to twice as much as the rate without the barrier as the dimensionless equivalent hydraulic conductivity decreases. Additionally, as the dimensionless length of the barrier increases, the withdrawal rate exhibits a significant increasing trend before reaching a plateau. In a rectangular aquifer, the pumping well located closer to the inland boundary and nearer to the axis of symmetry along the shore corresponds to a higher maximum sustainable withdrawal rate. Furthermore, the maximum sustainable withdrawal rate is an order of magnitude more sensitive to the aquifer aspect ratio and the dimensionless hydraulic parameter than to the dimensionless transverse dispersivity. These findings offer valuable insights for constructing less permeable barriers to migrate seawater intrusion and for deploying pumping wells in coastal areas. The proposed analytical framework provides a flexible basis for analyzing coastal aquifer problems involving pumping wells, aquifer heterogeneity, and complex boundary conditions.
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