Rainer Helmig
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View article: Mineralogical and chemical study of the salt alteration of masonry blocks in the baths of Antoninus ruins at Carthage, Tunisia
Mineralogical and chemical study of the salt alteration of masonry blocks in the baths of Antoninus ruins at Carthage, Tunisia Open
View article: Impact of Saturation on Evaporation-Driven Density Instabilities in Porous Media: Mathematical and Numerical Analysis
Impact of Saturation on Evaporation-Driven Density Instabilities in Porous Media: Mathematical and Numerical Analysis Open
Evaporation from a porous medium partially saturated with saline water, causes the salinity (salt concentration) to increase near the top of the porous medium as water leaves while salt stays behind. As the density of the water increases w…
View article: Vertex-centered control-volume mimetic finite difference methods
Vertex-centered control-volume mimetic finite difference methods Open
View article: The Role of Wind Velocity in Saline Water Evaporation from Porous Media and Surface Salt Crystallization Dynamics
The Role of Wind Velocity in Saline Water Evaporation from Porous Media and Surface Salt Crystallization Dynamics Open
View article: Self-Pumping Transpiration Cooling: A Joint Experimental and Numerical Study
Self-Pumping Transpiration Cooling: A Joint Experimental and Numerical Study Open
A joint experimental and numerical study is presented to close the current gap in fully coupled data and modeling capabilities for self-pumping transpiration cooling (SPTC). An experimental setup was developed to investigate the effects of…
View article: Regional-Scale Subsurface Modeling
Regional-Scale Subsurface Modeling Open
The subsurface is a critical foundation for society, providing essential resources such as water, minerals, and energy, while also offering storage capacity for resources and waste. Current subsurface use is expanding rapidly, leading to a…
View article: Data-Driven Closure Parametrizations with Metrics: Dispersive Transport
Data-Driven Closure Parametrizations with Metrics: Dispersive Transport Open
This work presents a data-driven framework for multi-scale parametrization of velocity-dependent dispersive transport in porous media. Pore-scale flow and transport simulations are conducted on periodic pore geometries, and volume averagin…
View article: A fully-implicit solving approach to an adaptive multi-scale model - coupling a vertical-equilibrium and full-dimensional model for compressible, multi-phase flow in porous media
A fully-implicit solving approach to an adaptive multi-scale model - coupling a vertical-equilibrium and full-dimensional model for compressible, multi-phase flow in porous media Open
Vertical equilibrium models have proven to be well suited for simulating fluid flow in subsurface porous media such as saline aquifers with caprocks. However, in most cases the dimensionally reduced model lacks the accuracy to capture the …
View article: Two-phase pore-network model for evaporation-driven salt precipitation -- representation and analysis of pore-scale processes
Two-phase pore-network model for evaporation-driven salt precipitation -- representation and analysis of pore-scale processes Open
Evaporation-driven salt precipitation occurs in different contexts and leads to challenges in case of e.g. soil salinization or stress-introducing precipitation in building material. During evaporation, brine in porous media gets concentra…
View article: A phase-field approach to model evaporation from porous media: Modeling and upscaling
A phase-field approach to model evaporation from porous media: Modeling and upscaling Open
View article: Applicability of the Vertical Equilibrium model to underground hydrogen injection and withdrawal
Applicability of the Vertical Equilibrium model to underground hydrogen injection and withdrawal Open
View article: Impact of saturation on evaporation-driven density instabilities in porous media: mathematical and numerical analysis
Impact of saturation on evaporation-driven density instabilities in porous media: mathematical and numerical analysis Open
Evaporation from a porous medium partially saturated with saline water, causes the salinity (salt concentration) to increase near the top of the porous medium as water leaves while salt stays behind. As the density of the water increases w…
View article: Vertex-Centered Control-Volume Mimetic Finite Difference Methods
Vertex-Centered Control-Volume Mimetic Finite Difference Methods Open
View article: Reproducing Damage to the Bowling Green Community Induced by 2021 Midwest Tornado Outbreak Using Combined Cm1 and Cfd
Reproducing Damage to the Bowling Green Community Induced by 2021 Midwest Tornado Outbreak Using Combined Cm1 and Cfd Open
View article: Mixed finite element projection methods for the unsteady Stokes equations
Mixed finite element projection methods for the unsteady Stokes equations Open
View article: Quantifying Salt Crystallization Impact on Evaporation Dynamics From Porous Surfaces
Quantifying Salt Crystallization Impact on Evaporation Dynamics From Porous Surfaces Open
We investigated the effects of salt crystallization on the dynamics of saline water evaporation in porous media. Water mass loss rates from sand columns supplied with NaCl solutions at three concentrations were monitored under controlled a…
View article: Mixed finite element projection methods for the unsteady Stokes equations
Mixed finite element projection methods for the unsteady Stokes equations Open
We develop $H$(div)-conforming mixed finite element methods for the unsteady Stokes equations modeling single-phase incompressible fluid flow. A projection method in the framework of the incremental pressure correction methodology is appli…
View article: Modeling and Analysis of Droplet Evaporation at the Interface of a Coupled Free-Flow–Porous Medium System
Modeling and Analysis of Droplet Evaporation at the Interface of a Coupled Free-Flow–Porous Medium System Open
Evaporation of droplets formed at the interface of a coupled free-flow–porous medium system enormously affects the exchange of mass, momentum, and energy between the two domains. In this work, we develop a model to describe multiple drople…
View article: Investigation of Different Throat Concepts for Precipitation Processes in Saturated Pore-Network Models
Investigation of Different Throat Concepts for Precipitation Processes in Saturated Pore-Network Models Open
The development of reliable mathematical models and numerical discretization methods is important for the understanding of salt precipitation in porous media, which is relevant for environmental problems like soil salinization. Models on t…
View article: Analysis of experimental and simulation data of evaporation‐driven isotopic fractionation in unsaturated porous media
Analysis of experimental and simulation data of evaporation‐driven isotopic fractionation in unsaturated porous media Open
Stable water isotopologs can add valuable information to the understanding of evaporation processes. The identification of the evaporation front from isotopolog concentration depth profiles under very dry soil conditions is of particular i…
View article: A fully-implicit solving approach to an adaptive multi-scale model -- coupling a vertical-equilibrium and full-dimensional model for compressible, multi-phase flow in porous media
A fully-implicit solving approach to an adaptive multi-scale model -- coupling a vertical-equilibrium and full-dimensional model for compressible, multi-phase flow in porous media Open
Vertical equilibrium models have proven to be well suited for simulating fluid flow in subsurface porous media such as saline aquifers with caprocks. However, in most cases the dimensionally reduced model lacks the accuracy to capture the …
View article: InterPore Journal Goes Online
InterPore Journal Goes Online Open
InterPore Journal is an international, peer-reviewed, open-access journal, entirely published and owned by The International Society for Porous Media (InterPore) focused on a wide range of topics related to porous media science and technol…
View article: Preventing Salt Precipitation in Soils through Density-Driven Salt Instabilities
Preventing Salt Precipitation in Soils through Density-Driven Salt Instabilities Open
Soil salinization causes severe problems in agriculture, especially in arid and semi-arid regions, as it leads to soil degradation and reduces plant growth. During evaporation from a saline-water-saturated soil, salt accumulates near the t…
View article: A mortar method for the coupled Stokes-Darcy problem using the MAC scheme for Stokes and mixed finite elements for Darcy
A mortar method for the coupled Stokes-Darcy problem using the MAC scheme for Stokes and mixed finite elements for Darcy Open
View article: Mixed Finite Element Projection Methods for the Unsteady Stokes Equations
Mixed Finite Element Projection Methods for the Unsteady Stokes Equations Open
View article: Estimation of Capillary‐Associated NAPL‐Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method
Estimation of Capillary‐Associated NAPL‐Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method Open
By employing kinetic interface sensitive (KIS) tracers, we investigate three different types of glass‐bead materials and three natural porous media systems to quantitatively characterize the influence of the porous‐medium grain‐, pore‐size…
View article: Data-Driven Closure Parametrizations with Metrics: Dispersive Transport
Data-Driven Closure Parametrizations with Metrics: Dispersive Transport Open
This work presents a data-driven framework for multi-scale parametrization of velocity-dependent dispersive transport in porous media. Pore-scale flow and transport simulations are conducted on periodic pore geometries, and volume-averagin…
View article: A new numerical mesoscopic scale one-domain approach solver for free fluid/porous medium interaction
A new numerical mesoscopic scale one-domain approach solver for free fluid/porous medium interaction Open
View article: A New Fully Implicit Two-Phase Pore-Network Model by Utilizing Regularization Strategies
A New Fully Implicit Two-Phase Pore-Network Model by Utilizing Regularization Strategies Open
In this paper, we address the expensive computational cost resulting from limited time-step sizes during numerical simulations of two-phase flow in porous media using dynamic pore-network models. To overcome this issue, we propose a numeri…
View article: A new numerical mesoscopic scale one-domain approach solver for free fluid/porous medium interaction
A new numerical mesoscopic scale one-domain approach solver for free fluid/porous medium interaction Open
A new numerical continuum \textit{one-domain} approach (ODA) solver is presented for the simulation of the transfer processes between a free fluid and a porous medium. The solver is developed in the \textit{mesoscopic} scale framework, whe…