Instantaneous heat transfer between different phases, known as local thermal equilibrium (LTE), is commonly assumed for modeling heat transfer in porous media. This assumption may not hold in certain technical and environmental applications, particularly with large temperature gradients, large differences in thermal properties, or high velocities. Local thermal non-equilibrium (LTNE) models aim to describe heat transfer proces...

Salt precipitation in porous media can negatively impact environmental systems. It enhances the evaporation process and thereby leads to a faster drying of soils. To address this, we introduce a dual-continuum modeling framework that enables the simulation of fluid flow in both the original, main porous structure, referred to as porous matrix, and the newly formed salt structure. We present two modeling strategies: (1) a coupl...

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 the porous medium properties, the flow conditions, and the interactions between solid and coolant on SPTC. Additionally, a two-reference-point, locally emissivity-corrected evaluation method...

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 averaging is used to isolate dispersive transport, producing parameters for the dispersive closure term at the representative elementary volume scale. After validation on unit cells with symmetric an...

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 dynamics of a system. While conventional full-dimensional models have the ability to represent dynamics, they come at the cost of high computational effort. We aim to combine the efficiency o...

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 droplets’ evaporation at the interface, in which new sets of coupling conditions including the evaporating droplets are developed to describe the interactions between the free flow and the porous m...

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 the pore scale are necessary to represent local heterogeneities in precipitation and to include the influence of solution-air-solid interfaces. A pore-network model for saturated flow, which i...

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 numerical method for dynamic pore-network models using a fully implicit approach. The proposed method introduces a regularization strategy considering the historical fluid configuration at the pore...

Coupled free-flow–porous medium systems are of great importance in various natural and industrial applications. Modeling of such systems is always challenging, especially when droplets form at the interface between the two domains. We propose a new concept to take droplet formation, growth and detachment at the interface into account. In this concept, we use pore-network modeling to describe the porous medium and the Navier–St...

For improved operating conditions of a polymer electrolyte membrane (PEM) fuel cell, a sophisticated water management is crucial. Therefore, it is necessary to understand the transport mechanisms of water throughout the cell constituents especially on the cathode side, where the excess water has to be removed. Pore-scale modeling of diffusion layers and gas distributor has been established as a favorable technique to investiga...

Fluid flow through layered materials with different wetting behavior is observed in a wide range of applications in biological, environmental and technical systems. Therefore, it is necessary to understand the occuring transport mechanisms of the fluids at the interface between the layered constituents. Of special interest is the water transport in polymer electrolyte membrane fuel cells. Here, it is necessary to understand th...

Soil salinization is a major cause of soil degradation and hampers plant growth. For soils saturated with saline water, the evaporation of water induces accumulation of salt near the top of the soil. The remaining liquid gets an increasingly larger density due to the accumulation of salt, giving a gravitationally unstable situation, where instabilities in the form of fingers can form. These fingers can, hence, lead to a net do...

We present a dual network model to simulate coupled single-phase flow and energy transport in porous media including conditions under which local thermal equilibrium cannot be assumed. The models target applications such as the simulation of catalytic reactors, micro-fluidic experiments, or micro-cooling devices. The new technique is based on a recently developed algorithm that extracts both the pore space and the solid grain...

Turbulence transportation across permeable interfaces is investigated using direct numerical simulation, and the connection between the turbulent surface flow and the pore flow is explored. The porous media domain is constructed with an in-line arranged circular cylinder array. The effects of Reynolds number and porosity are also investigated by comparing cases with two Reynolds numbers ( $$Re\approx 3000,6000$$ R e ≈ 3000 , 6...

Exchange processes between a turbulent free flow and a porous media flow are sensitive to the flow dynamics in both flow regimes, as well as to the interface that separates them. Resolving these complex exchange processes across irregular interfaces is key in understanding many natural and engineered systems. With soil–water evaporation as the natural application of interest, the coupled behavior and exchange between flow regi...