Pub Date : 2025-09-26DOI: 10.1016/j.advwatres.2025.105134
Shida Zheng , Jinsheng Wang , Chengzhi Wang , Jiawei Liu , Rui Zuo , Guanlan Wu , Xiaofan Yang , Minghao Pan , Hao Wang , Guangrong Hu
Reservoir flow properties are crucial for sustaining the magnitude and effectiveness of compressed gas energy storage in aquifer. Although changes in flow properties due to CO2 injection have received attention, the impact of compressed air injection-induced geochemical reactions on flow properties has been overlooked. This study presents a series of controlled experiments with different reaction conditions to reveal the effects of pore-scale mechanisms of geochemical reactions on pore structure and flow properties. Although air injection enhanced the oxidation potential of the brine, oxidation reactions were limited due to the absence of oxidation-sensitive minerals. Integrated analyses of fluid chemistry, mineralogical characterization, and kinetic reaction modeling indicated that albite dissolution was the primary process governing rock property alteration. Albite dissolution occurring in pores and throats drives pore structure evolution and interconnects isolated pores, thereby leading to a significant increase in the total and connected porosity. As a result, an increase in permeability was observed. The brine percolating through the larger pores initiates the albite dissolution, further widens the seepage pathways and enhances the fluid flow. Ultimately, a quantitative relationship between permeability and porosity influenced by geochemical reactions was established. This study highlights the significance of geochemical reactions in compressed air energy storage in aquifer and provides essential theoretical insights for future numerical simulations and commercial exploitation.
{"title":"Effects of geochemical reactions on flow properties during compressed air energy storage in aquifer","authors":"Shida Zheng , Jinsheng Wang , Chengzhi Wang , Jiawei Liu , Rui Zuo , Guanlan Wu , Xiaofan Yang , Minghao Pan , Hao Wang , Guangrong Hu","doi":"10.1016/j.advwatres.2025.105134","DOIUrl":"10.1016/j.advwatres.2025.105134","url":null,"abstract":"<div><div>Reservoir flow properties are crucial for sustaining the magnitude and effectiveness of compressed gas energy storage in aquifer. Although changes in flow properties due to CO<sub>2</sub> injection have received attention, the impact of compressed air injection-induced geochemical reactions on flow properties has been overlooked. This study presents a series of controlled experiments with different reaction conditions to reveal the effects of pore-scale mechanisms of geochemical reactions on pore structure and flow properties. Although air injection enhanced the oxidation potential of the brine, oxidation reactions were limited due to the absence of oxidation-sensitive minerals. Integrated analyses of fluid chemistry, mineralogical characterization, and kinetic reaction modeling indicated that albite dissolution was the primary process governing rock property alteration. Albite dissolution occurring in pores and throats drives pore structure evolution and interconnects isolated pores, thereby leading to a significant increase in the total and connected porosity. As a result, an increase in permeability was observed. The brine percolating through the larger pores initiates the albite dissolution, further widens the seepage pathways and enhances the fluid flow. Ultimately, a quantitative relationship between permeability and porosity influenced by geochemical reactions was established. This study highlights the significance of geochemical reactions in compressed air energy storage in aquifer and provides essential theoretical insights for future numerical simulations and commercial exploitation.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105134"},"PeriodicalIF":4.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-25DOI: 10.1016/j.advwatres.2025.105125
Daniel Stalder, Shangyi Cao, Daniel W. Meyer, Patrick Jenny
Flow in fractured porous media is associated with high uncertainty, particularly regarding fracture properties and their overall configuration within the domain. This is especially pronounced for disconnected fractures of smaller yet comparable size to the domain. Consequently, ensemble averages are often used to capture this statistical variability and predict the expected behavior. This leads to enormous computational costs, as flow simulations of single realizations with millions of fractures are extremely expensive; and much more so full Monte Carlo studies involving hundreds of realizations. Alternatively, a recently introduced model aims to directly estimate expected flow rates and pressure fields. The model involves few degrees of freedom, leading to low-cost computations. This is achieved by using integro-differential equations involving non-local kernel functions that encompass the statistical information of fractures. So far this statistical integro-differential fracture model (Sid-FM) considers only ensembles with identical fractures having constant aperture and lengths. In this paper Sid-FM is extended to account for arbitrary fracture aperture profiles and reservoirs with fractures following specified length distributions, which is a crucial step towards applications with realistic fractured reservoirs. In a series of numerical experiments, it is demonstrated that the Sid-FM’s predictions are in excellent agreement with Monte Carlo reference data, which are based on many fracture-resolving simulations. The applicability is demonstrated through statistically one-dimensional cases, laying crucial groundwork for 2D and 3D extensions. Future work will focus on further generalizations and extensions such as transport processes and 2D/3D applications.
{"title":"Statistical integro-differential fracture model (Sid-FM) for isolated fractures with variable apertures and lengths","authors":"Daniel Stalder, Shangyi Cao, Daniel W. Meyer, Patrick Jenny","doi":"10.1016/j.advwatres.2025.105125","DOIUrl":"10.1016/j.advwatres.2025.105125","url":null,"abstract":"<div><div>Flow in fractured porous media is associated with high uncertainty, particularly regarding fracture properties and their overall configuration within the domain. This is especially pronounced for disconnected fractures of smaller yet comparable size to the domain. Consequently, ensemble averages are often used to capture this statistical variability and predict the expected behavior. This leads to enormous computational costs, as flow simulations of single realizations with millions of fractures are extremely expensive; and much more so full Monte Carlo studies involving hundreds of realizations. Alternatively, a recently introduced model aims to directly estimate expected flow rates and pressure fields. The model involves few degrees of freedom, leading to low-cost computations. This is achieved by using integro-differential equations involving non-local kernel functions that encompass the statistical information of fractures. So far this statistical integro-differential fracture model (Sid-FM) considers only ensembles with identical fractures having constant aperture and lengths. In this paper Sid-FM is extended to account for arbitrary fracture aperture profiles and reservoirs with fractures following specified length distributions, which is a crucial step towards applications with realistic fractured reservoirs. In a series of numerical experiments, it is demonstrated that the Sid-FM’s predictions are in excellent agreement with Monte Carlo reference data, which are based on many fracture-resolving simulations. The applicability is demonstrated through statistically one-dimensional cases, laying crucial groundwork for 2D and 3D extensions. Future work will focus on further generalizations and extensions such as transport processes and 2D/3D applications.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105125"},"PeriodicalIF":4.2,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-24DOI: 10.1016/j.advwatres.2025.105124
Louisa Pawusch , Stefania Scheurer , Wolfgang Nowak , Reed M. Maxwell
Finding the initial depth-to-water table (DTWT) configuration of a catchment is a critical challenge when simulating the hydrological cycle with integrated models, significantly impacting simulation outcomes. Traditionally, this involves iterative spin-up computations, where the model runs under constant atmospheric settings until steady-state is achieved. These so-called model spin-ups are computationally expensive, often requiring many years of simulated time, particularly when the initial DTWT configuration is far from steady state.
To accelerate the model spin-up process we developed HydroStartML, a machine learning emulator trained on steady-state DTWT configurations across the contiguous United States. HydroStartML predicts, based on available data like conductivity and surface slopes, a DTWT configuration of the respective watershed, which can be used as an initial DTWT.
Our results show that initializing spin-up computations with HydroStartML predictions leads to faster convergence than with other initial configurations like spatially constant DTWTs. The emulator accurately predicts configurations close to steady state, even for terrain configurations not seen in training, and allows especially significant reductions in computational spin-up effort in regions with deep DTWTs. This work opens the door for hybrid approaches that blend machine learning and traditional simulation, enhancing predictive accuracy and efficiency in hydrology for improving water resource management and understanding complex environmental interactions.
{"title":"HydroStartML: A combined machine learning and physics-based approach to reduce hydrological model spin-up time","authors":"Louisa Pawusch , Stefania Scheurer , Wolfgang Nowak , Reed M. Maxwell","doi":"10.1016/j.advwatres.2025.105124","DOIUrl":"10.1016/j.advwatres.2025.105124","url":null,"abstract":"<div><div>Finding the initial depth-to-water table (DTWT) configuration of a catchment is a critical challenge when simulating the hydrological cycle with integrated models, significantly impacting simulation outcomes. Traditionally, this involves iterative spin-up computations, where the model runs under constant atmospheric settings until steady-state is achieved. These so-called model spin-ups are computationally expensive, often requiring many years of simulated time, particularly when the initial DTWT configuration is far from steady state.</div><div>To accelerate the model spin-up process we developed <em>HydroStartML</em>, a machine learning emulator trained on steady-state DTWT configurations across the contiguous United States. <em>HydroStartML</em> predicts, based on available data like conductivity and surface slopes, a DTWT configuration of the respective watershed, which can be used as an initial DTWT.</div><div>Our results show that initializing spin-up computations with <em>HydroStartML</em> predictions leads to faster convergence than with other initial configurations like spatially constant DTWTs. The emulator accurately predicts configurations close to steady state, even for terrain configurations not seen in training, and allows especially significant reductions in computational spin-up effort in regions with deep DTWTs. This work opens the door for hybrid approaches that blend machine learning and traditional simulation, enhancing predictive accuracy and efficiency in hydrology for improving water resource management and understanding complex environmental interactions.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105124"},"PeriodicalIF":4.2,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-24DOI: 10.1016/j.advwatres.2025.105123
Ayomikun Bello , Abdolreza Kharaghani, Evangelos Tsotsas
Evaporation in porous media plays a critical role in systems where optimizing evaporation rates and patterns is vital. Heterogeneous wettability can significantly influence evaporation dynamics by altering capillary forces and liquid connectivity; however, its specific effects on evaporation front morphology, capillary pressure–saturation relationships, and the transition to the falling-rate regime are not well understood. This study addresses this gap by using a modeling framework to simulate evaporation in mixed-wet porous media. The approach combines a three-dimensional pore-network model with a spatially-resolved non-equilibrium continuum model on an identical voxel-based domain. The porous medium is assigned random contact angles ranging from 30°to 150°. Capillary-driven flow and evaporation are simulated, and key metrics such as liquid saturation, capillary pressure, and relative permeability are monitored. Our results show a two-stage drying process. In the initial stage, a highly connected liquid network sustains capillary-driven evaporation with high flux. Over time, liquid clusters become isolated and wet pockets persist, slowing evaporation and inducing a falling-rate regime. Heterogeneous wettability produces a ramified evaporation front, alters capillary pressure dynamics, and affects the evolution of relative permeability. These findings improve our understanding of evaporation kinetics in mixed-wet porous media. They validate the use of a dynamic capillary pressure formulation in continuum models and inform improved modeling of evaporation in environmental and industrial porous materials.
{"title":"Comparative pore and continuum-scale modeling of evaporation in mixed wettability porous media","authors":"Ayomikun Bello , Abdolreza Kharaghani, Evangelos Tsotsas","doi":"10.1016/j.advwatres.2025.105123","DOIUrl":"10.1016/j.advwatres.2025.105123","url":null,"abstract":"<div><div>Evaporation in porous media plays a critical role in systems where optimizing evaporation rates and patterns is vital. Heterogeneous wettability can significantly influence evaporation dynamics by altering capillary forces and liquid connectivity; however, its specific effects on evaporation front morphology, capillary pressure–saturation relationships, and the transition to the falling-rate regime are not well understood. This study addresses this gap by using a modeling framework to simulate evaporation in mixed-wet porous media. The approach combines a three-dimensional pore-network model with a spatially-resolved non-equilibrium continuum model on an identical voxel-based domain. The porous medium is assigned random contact angles ranging from 30°to 150°. Capillary-driven flow and evaporation are simulated, and key metrics such as liquid saturation, capillary pressure, and relative permeability are monitored. Our results show a two-stage drying process. In the initial stage, a highly connected liquid network sustains capillary-driven evaporation with high flux. Over time, liquid clusters become isolated and wet pockets persist, slowing evaporation and inducing a falling-rate regime. Heterogeneous wettability produces a ramified evaporation front, alters capillary pressure dynamics, and affects the evolution of relative permeability. These findings improve our understanding of evaporation kinetics in mixed-wet porous media. They validate the use of a dynamic capillary pressure formulation in continuum models and inform improved modeling of evaporation in environmental and industrial porous materials.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105123"},"PeriodicalIF":4.2,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coastal and hydrologic floods are distinct yet interconnected phenomena, driven by oceanic and terrestrial processes, respectively. Their interaction—known as compound flooding—occurs when storm surge, heavy precipitation, and river flow coincide, significantly amplifying flood impacts in coastal riverine regions. These interactions give rise to a transition zone, where coastal and hydrologic flood processes converge, resulting in complex, prolonged inundation that is challenging to predict using traditional hydrodynamic models. Accurately delineating this zone is essential for improving flood risk assessment and mitigation strategies. In this study, we employ deep learning to quantify the relative contributions of terrestrial hydrologic and coastal flood drivers, enabling spatial delineation of the transition zone within Galveston Bay in Texas. This data-driven approach addresses the limitations of conventional models and supports more effective flood-resilience planning for vulnerable coastal communities. Our results reveal spatial patterns of flood driver dominance, with storm tide influencing coastal zones and river flow playing a greater role inland. The use of SHapley Additive exPlanations (SHAP) enables the delineation of a transition zone where no single driver dominates, underscoring the importance of compound flood modeling in such areas. This framework offers a scalable and interpretable solution for identifying high-risk zones, enhancing the precision of flood risk assessments, and informing targeted mitigation efforts in coastal regions.
{"title":"Spatial delineation of the compound flood transition zone using deep learning","authors":"Farnaz Yarveysi , Francisco Gomez Diaz , Hamed Moftakhari , Hamid Moradkhani","doi":"10.1016/j.advwatres.2025.105131","DOIUrl":"10.1016/j.advwatres.2025.105131","url":null,"abstract":"<div><div>Coastal and hydrologic floods are distinct yet interconnected phenomena, driven by oceanic and terrestrial processes, respectively. Their interaction—known as compound flooding—occurs when storm surge, heavy precipitation, and river flow coincide, significantly amplifying flood impacts in coastal riverine regions. These interactions give rise to a transition zone, where coastal and hydrologic flood processes converge, resulting in complex, prolonged inundation that is challenging to predict using traditional hydrodynamic models. Accurately delineating this zone is essential for improving flood risk assessment and mitigation strategies. In this study, we employ deep learning to quantify the relative contributions of terrestrial hydrologic and coastal flood drivers, enabling spatial delineation of the transition zone within Galveston Bay in Texas. This data-driven approach addresses the limitations of conventional models and supports more effective flood-resilience planning for vulnerable coastal communities. Our results reveal spatial patterns of flood driver dominance, with storm tide influencing coastal zones and river flow playing a greater role inland. The use of SHapley Additive exPlanations (SHAP) enables the delineation of a transition zone where no single driver dominates, underscoring the importance of compound flood modeling in such areas. This framework offers a scalable and interpretable solution for identifying high-risk zones, enhancing the precision of flood risk assessments, and informing targeted mitigation efforts in coastal regions.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105131"},"PeriodicalIF":4.2,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-22DOI: 10.1016/j.advwatres.2025.105129
Hojung You , Rafael O. Tinoco
This study investigates the effect of submergence ratio on the transport of exogenous particles in streams, targeting particles with density and diameter representative of microplastic and eggs of invasive species, which are of major concern in management of aquatic environments. Transport of two types of surrogate particles, with mean diameters of 1 and 4.8 mm and specific gravities of 1.00 and 1.0025, respectively, was assessed through experiments in a laboratory flume. Submerged obstacles with simplified geometries were mounted on the bed of a flume to represent in-stream obstructions. Image processing techniques, Particle Image Velocimetry (PIV) and Lagrangian Particle Tracking, were used to obtain flow velocity fields and particle trajectories. Angular momentum theorem was used to quantify the emergence of coherent eddies, which increase particle entry and timespans between submerged obstacles. Two indices are introduced: particle entry ratio and timespan of particles, which depend on particle characteristics, submergence ratio, and gap length. The study provides insights into the fundamental physics of particle transport, offering practical implications for aquatic debris and invasive species management, including effective monitoring locations and trap designs.
{"title":"Submergence ratio and spacing between in-stream obstructions determine capture and accumulation of drifting particles in rivers","authors":"Hojung You , Rafael O. Tinoco","doi":"10.1016/j.advwatres.2025.105129","DOIUrl":"10.1016/j.advwatres.2025.105129","url":null,"abstract":"<div><div>This study investigates the effect of submergence ratio on the transport of exogenous particles in streams, targeting particles with density and diameter representative of microplastic and eggs of invasive species, which are of major concern in management of aquatic environments. Transport of two types of surrogate particles, with mean diameters of 1 and 4.8 mm and specific gravities of 1.00 and 1.0025, respectively, was assessed through experiments in a laboratory flume. Submerged obstacles with simplified geometries were mounted on the bed of a flume to represent in-stream obstructions. Image processing techniques, Particle Image Velocimetry (PIV) and Lagrangian Particle Tracking, were used to obtain flow velocity fields and particle trajectories. Angular momentum theorem was used to quantify the emergence of coherent eddies, which increase particle entry and timespans between submerged obstacles. Two indices are introduced: particle entry ratio and timespan of particles, which depend on particle characteristics, submergence ratio, and gap length. The study provides insights into the fundamental physics of particle transport, offering practical implications for aquatic debris and invasive species management, including effective monitoring locations and trap designs.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105129"},"PeriodicalIF":4.2,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-20DOI: 10.1016/j.advwatres.2025.105127
Ruichang Guo, Hongsheng Wang, Reza Ershadnia, Seyyed A. Hosseini
Subsurface rocks with anisotropic pore structures that exhibit anisotropic absolute permeability also tend to display anisotropic behavior in relative permeability. As a key input for reservoir simulation, relative permeability is essential for evaluating and optimizing the performance of subsurface energy systems. However, this anisotropy is often overlooked in simulations due to the complexity involved in its characterization under varying conditions. A major challenge lies in the fact that relative permeability anisotropy is influenced by multiple factors, including fluid saturation, rock wettability, and the capillary number of the displacement process. Unlike absolute permeability, which can be succinctly characterized using an anisotropy ratio, relative permeability lacks a similarly concise representation. This study investigated how these factors affect relative permeability anisotropy in the context of underground hydrogen storage and provides insights for its modeling. Three types of porous media were designed to represent key forms of anisotropic pore structures: stratified sedimentary structure (SSS), directionally varying pore geometry (DVPG), and oriented fracture network (OFN). Direct pore-scale simulations using the lattice Boltzmann method were conducted to examine the anisotropic behavior of relative permeability in each medium. The degree of anisotropy was quantified using a relative permeability anisotropy ratio, , and its dependence on water saturation and wettability was analyzed. Results showed that in the SSS medium varied significantly with water saturation and wettability, while in DVPG and OFN media remained largely insensitive to these factors. A geometric average anisotropy ratio, , was proposed to characterize the overall degree of relative permeability anisotropy under specific wetting conditions. This metric showed that , was greater than 1 for all porous media types and was comparable in magnitude to the absolute permeability ratio. These findings suggested that neglecting relative permeability anisotropy in reservoir simulations could introduce significant errors. The results enhanced theoretical understanding of two-phase flow in complex porous media and offered practical guidance for reservoir-scale modeling in anisotropic formations.
{"title":"Anisotropy of two-phase relative permeability in porous media and its implications for underground hydrogen storage","authors":"Ruichang Guo, Hongsheng Wang, Reza Ershadnia, Seyyed A. Hosseini","doi":"10.1016/j.advwatres.2025.105127","DOIUrl":"10.1016/j.advwatres.2025.105127","url":null,"abstract":"<div><div>Subsurface rocks with anisotropic pore structures that exhibit anisotropic absolute permeability also tend to display anisotropic behavior in relative permeability. As a key input for reservoir simulation, relative permeability is essential for evaluating and optimizing the performance of subsurface energy systems. However, this anisotropy is often overlooked in simulations due to the complexity involved in its characterization under varying conditions. A major challenge lies in the fact that relative permeability anisotropy is influenced by multiple factors, including fluid saturation, rock wettability, and the capillary number of the displacement process. Unlike absolute permeability, which can be succinctly characterized using an anisotropy ratio, relative permeability lacks a similarly concise representation. This study investigated how these factors affect relative permeability anisotropy in the context of underground hydrogen storage and provides insights for its modeling. Three types of porous media were designed to represent key forms of anisotropic pore structures: stratified sedimentary structure (SSS), directionally varying pore geometry (DVPG), and oriented fracture network (OFN). Direct pore-scale simulations using the lattice Boltzmann method were conducted to examine the anisotropic behavior of relative permeability in each medium. The degree of anisotropy was quantified using a relative permeability anisotropy ratio, <span><math><msub><mi>R</mi><mrow><mi>r</mi><mi>A</mi></mrow></msub></math></span>, and its dependence on water saturation and wettability was analyzed. Results showed that <span><math><msub><mi>R</mi><mrow><mi>r</mi><mi>A</mi></mrow></msub></math></span> in the SSS medium varied significantly with water saturation and wettability, while <span><math><msub><mi>R</mi><mrow><mi>r</mi><mi>A</mi></mrow></msub></math></span> in DVPG and OFN media remained largely insensitive to these factors. A geometric average anisotropy ratio, <span><math><msub><mover><mi>R</mi><mo>¯</mo></mover><mrow><mi>r</mi><mi>A</mi></mrow></msub></math></span>, was proposed to characterize the overall degree of relative permeability anisotropy under specific wetting conditions. This metric showed that <span><math><msub><mover><mi>R</mi><mo>¯</mo></mover><mrow><mi>r</mi><mi>A</mi></mrow></msub></math></span>, was greater than 1 for all porous media types and was comparable in magnitude to the absolute permeability ratio. These findings suggested that neglecting relative permeability anisotropy in reservoir simulations could introduce significant errors. The results enhanced theoretical understanding of two-phase flow in complex porous media and offered practical guidance for reservoir-scale modeling in anisotropic formations.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105127"},"PeriodicalIF":4.2,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-20DOI: 10.1016/j.advwatres.2025.105126
Chengwei Hu , Yujiao Liu , Minghui Yu
Meandering rivers sculpt landscapes and foster diverse ecosystems, with secondary flows in bends exerting a pivotal influence on sediment transport and channel morphology. Although the Froude number typically remains below 0.3 in natural meanders, the interplay of secondary flows under these low-Froude conditions is still poorly understood. This study addresses this knowledge gap by systematically examining the influence of Froude numbers (Fr = 0.12-0.21) on secondary flow structures in sharply curved channels through high-resolution flume experiments and numerical simulations. Results reveal that even slight variations in Froude number can markedly alter vortex dynamics and secondary flow complexity, underscoring a delicate balance between inertial and turbulent forces. In particular, the stability of S2-type secondary flows depends on the precise alignment of advective, centrifugal, and turbulence-induced vorticity. Minor shifts in inertial forcing can rapidly destabilize S2, leading to significant changes in velocity distributions. Additionally, a time or spatial lag between the onset of secondary circulation and the point of maximum velocity inversion points to a dynamic, two-way feedback between the secondary flow and the main flow, evolving from robust vortex growth at lower Fr to flow decay at higher Fr. These findings advance our understanding of secondary flow mechanisms in natural rivers and offer practical insights for river engineering and flood management, informing more effective strategies for sediment control and bank stability.
{"title":"Influence of froude number on the development and evolution of secondary flows in a sharply curved bend: An experimental and numerical study","authors":"Chengwei Hu , Yujiao Liu , Minghui Yu","doi":"10.1016/j.advwatres.2025.105126","DOIUrl":"10.1016/j.advwatres.2025.105126","url":null,"abstract":"<div><div>Meandering rivers sculpt landscapes and foster diverse ecosystems, with secondary flows in bends exerting a pivotal influence on sediment transport and channel morphology. Although the Froude number typically remains below 0.3 in natural meanders, the interplay of secondary flows under these low-Froude conditions is still poorly understood. This study addresses this knowledge gap by systematically examining the influence of Froude numbers (<em>Fr</em> = 0.12-0.21) on secondary flow structures in sharply curved channels through high-resolution flume experiments and numerical simulations. Results reveal that even slight variations in Froude number can markedly alter vortex dynamics and secondary flow complexity, underscoring a delicate balance between inertial and turbulent forces. In particular, the stability of S2-type secondary flows depends on the precise alignment of advective, centrifugal, and turbulence-induced vorticity. Minor shifts in inertial forcing can rapidly destabilize S2, leading to significant changes in velocity distributions. Additionally, a time or spatial lag between the onset of secondary circulation and the point of maximum velocity inversion points to a dynamic, two-way feedback between the secondary flow and the main flow, evolving from robust vortex growth at lower <em>Fr</em> to flow decay at higher <em>Fr</em>. These findings advance our understanding of secondary flow mechanisms in natural rivers and offer practical insights for river engineering and flood management, informing more effective strategies for sediment control and bank stability.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105126"},"PeriodicalIF":4.2,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-17DOI: 10.1016/j.advwatres.2025.105120
Tongchao Nan , Tianwei Hu , Zichen Wang , Jiangjiang Zhang , Jina Yin , Yifan Xie , Jichun Wu , Chunhui Lu
Fractures critically influence fluid flow and heat transfer in geothermal reservoirs, necessitating accurate and efficient simulation tools for resource management. Here we introduce ETH, an open-source Embedded Discrete Fracture Model (EDFM) module integrated with the MATLAB Reservoir Simulation Toolbox (MRST), enabling coupled hydrothermal simulations in both 2D and 3D fractured porous media. ETH extends prior EDFM frameworks by incorporating heat transfer and variable fluid properties, validated through four benchmarks ranging from analytical single-fracture cases to complex 3D fracture networks. Results demonstrate high accuracy (relative errors mostly <1 %) and computational efficiency, with 20–50 % reduced cost compared to FEM-based discrete fracture models. ETH’s modular design supports mesh/time convergence control and integration of additional physics, facilitating robust modeling of heterogeneous and anisotropic reservoirs. This tool advances accessible, high-fidelity simulation capabilities for geothermal reservoir characterization, development, and uncertainty quantification.
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Pub Date : 2025-09-16DOI: 10.1016/j.advwatres.2025.105122
Morteza Dejam
Tracer tests are widely performed for the characterization of reservoir properties during the hydraulic fracturing operation. The dispersion of the tracer depends on the interaction of the proppant-packed hydraulic fracture and the tight porous medium through the naturally porous walls. However, the effects of the interaction of the porous walls and dynamics of flow in the proppant-packed hydraulic fracture on the tracer dispersion and reservoir dynamic mass/heat storage capacity have not yet been reported in the literature. In this work, the tracer dispersion in a proppant-packed hydraulic fracture surrounded by a tight porous medium is theoretically modeled and the dynamic storage capacity is evaluated. The Darcy-Brinkman equation is used to describe the fully developed laminar Stokes fluid flow in the proppant-packed hydraulic fracture. We used the Taylor dispersion theory and Reynolds decomposition approach to derive the exact equivalent transport parameters, including dispersion and advection coefficients, as well as the storage capacity of the tight porous medium. It is found that the tracer dispersion is controlled by the Darcy and the Peclet numbers in the proppant-packed hydraulic fracture. The results indicate that the ratio of tracer dispersion in the proppant-packed hydraulic fracture with porous walls to that with nonporous walls ranges from zero for very small Darcy numbers to 0.3 for large Darcy numbers. The ratio of the advection velocity in the proppant-packed hydraulic fracture with porous walls to that with nonporous walls ranges from unity for very small Darcy numbers to 7/5 for large Darcy numbers. The results also indicate that tracer mass storage capacity in the tight porous medium increases as the Peclet number for fluid flow in the proppant-packed hydraulic fracture increases. Conversely, storage decreases as the Darcy number in the proppant-packed hydraulic fracture rises. A comparison reveals that a flow transport model based on proppant-free hydraulic fracture may lead to the overestimation of the tracer mass/heat storage capacity. The findings of this study pave the way to advance our understanding of tracer tests for evaluating reservoir characteristics during fracturing operations in enhanced geothermal systems.
{"title":"Modeling tracer dispersion in a coupled system composed of a proppant-packed hydraulic fracture and a tight porous medium","authors":"Morteza Dejam","doi":"10.1016/j.advwatres.2025.105122","DOIUrl":"10.1016/j.advwatres.2025.105122","url":null,"abstract":"<div><div>Tracer tests are widely performed for the characterization of reservoir properties during the hydraulic fracturing operation. The dispersion of the tracer depends on the interaction of the proppant-packed hydraulic fracture and the tight porous medium through the naturally porous walls. However, the effects of the interaction of the porous walls and dynamics of flow in the proppant-packed hydraulic fracture on the tracer dispersion and reservoir dynamic mass/heat storage capacity have not yet been reported in the literature. In this work, the tracer dispersion in a proppant-packed hydraulic fracture surrounded by a tight porous medium is theoretically modeled and the dynamic storage capacity is evaluated. The Darcy-Brinkman equation is used to describe the fully developed laminar Stokes fluid flow in the proppant-packed hydraulic fracture. We used the Taylor dispersion theory and Reynolds decomposition approach to derive the exact equivalent transport parameters, including dispersion and advection coefficients, as well as the storage capacity of the tight porous medium. It is found that the tracer dispersion is controlled by the Darcy and the Peclet numbers in the proppant-packed hydraulic fracture. The results indicate that the ratio of tracer dispersion in the proppant-packed hydraulic fracture with porous walls to that with nonporous walls ranges from zero for very small Darcy numbers to 0.3 for large Darcy numbers. The ratio of the advection velocity in the proppant-packed hydraulic fracture with porous walls to that with nonporous walls ranges from unity for very small Darcy numbers to 7/5 for large Darcy numbers. The results also indicate that tracer mass storage capacity in the tight porous medium increases as the Peclet number for fluid flow in the proppant-packed hydraulic fracture increases. Conversely, storage decreases as the Darcy number in the proppant-packed hydraulic fracture rises. A comparison reveals that a flow transport model based on proppant-free hydraulic fracture may lead to the overestimation of the tracer mass/heat storage capacity. The findings of this study pave the way to advance our understanding of tracer tests for evaluating reservoir characteristics during fracturing operations in enhanced geothermal systems.</div></div>","PeriodicalId":7614,"journal":{"name":"Advances in Water Resources","volume":"206 ","pages":"Article 105122"},"PeriodicalIF":4.2,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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