Numerical simulations and process analysis of CO2 enrichement in the vadose zone and the gas-water interface of karstic systems

PN 1-5 (II)

Project description

The project investigates CO₂ enrichment in the vadose zone and at the gas–water interface of karst systems using numerical simulation, process analysis, and machine learning. Elevated CO₂ levels in karst caves are influenced by microbial activity, temperature, and limited ventilation, with gravity-driven segregation playing a role. A key site in Slovenia shows rapid re-establishment of high CO₂ levels after mixing events, suggesting long-term accumulation in conductive fractures.

The study will develop a conceptual model and a detailed numerical simulation that couples gas flow in cave passages with a discrete fracture–matrix model. The multiphase, multicomponent system (water, air, CO₂) will form the basis for creating surrogate models that enable machine-learning-based process identification, supported by both existing and new data.

Additional fieldwork is planned at a ponor in the Franconian Jura to study CO₂ dissolution at the gas–water interface under dry conditions, and at the Laichinger cave (Swabian Jura) to explore the correlation between CO₂ and radon concentrations via time-resolved measurements.

The project aligns with SimTech research goals by contributing to knowledge-integrated modeling (RQ1), enabling data-driven surrogate models (RQ2), and supporting the development of interpretable geosystem models (RQ3).

Project information

Project title Numerical simulations and process analysis of CO2 enrichement in the vadose zone and the gas-water interface of karstic systems
Project leaders Holger Claas
Project staff Vivien Langhans, doctoral researcher
Project duration September 2024 - December 2025
Project number PN 1-5 (II)
  • Preceding project 1-5
    Dispersion concept for interface closures in the context of coupling free-flow and porous-media multiphase flow on the REV scale

Publications of PN 1-5 and PN 1-5 (II)

  1. 2024

    1. C. Aricò, R. Helmig, D. Puleo, and M. Schneider, “A new numerical mesoscopic scale one-domain approach solver for free fluid/porous medium interaction,” Computer Methods in Applied Mechanics and Engineering, vol. 419, p. 116655, Feb. 2024, doi: 10.1016/j.cma.2023.116655.

  2. 2023

    1. S. Kiemle, K. Heck, E. Coltman, and R. Helmig, “Stable Water Isotopologue Fractionation During Soil‐Water Evaporation: Analysis Using a Coupled Soil‐Atmosphere Model,” Water Resources Research, vol. 59, Art. no. 2, Feb. 2023, doi: 10.1029/2022wr032385.
    2. M. Schneider, D. Gläser, K. Weishaupt, E. Coltman, B. Flemisch, and R. Helmig, “Coupling staggered-grid and vertex-centered finite-volume methods for coupled porous-medium free-flow problems,” Journal of Computational Physics, vol. 482, p. 112042, Jun. 2023, doi: 10.1016/j.jcp.2023.112042.

  3. 2022

    1. W. Wang, A. Lozano-Durán, R. Helmig, and X. Chu, “Spatial and spectral characteristics of information flux between turbulent boundary layers and porous media,” Journal of Fluid Mechanics, vol. 949, Sep. 2022, doi: 10.1017/jfm.2022.770.
    2. J. Eller, T. Sauerborn, B. Becker, I. Buntic, J. Gross, and R. Helmig, “Modeling Subsurface Hydrogen Storage With Transport Properties From Entropy Scaling Using the PC‐SAFT Equation of State,” Water Resources Research, vol. 58, Art. no. 4, 2022, doi: 10.1029/2021wr030885.

  4. 2021

    1. T. Koch, H. Wu, and M. Schneider, “Nonlinear mixed-dimension model for embedded tubular networks with application to root water uptake,” Journal of Computational Physics, p. 110823, Nov. 2021, doi: 10.1016/j.jcp.2021.110823.
    2. X. Chu, W. Wang, G. Yang, A. Terzis, R. Helmig, and B. Weigand, “Transport of Turbulence Across Permeable Interface in a Turbulent Channel Flow: Interface-Resolved Direct Numerical Simulation,” Transport in Porous Media, vol. 136, Art. no. 1, 2021, doi: 10.1007/s11242-020-01506-w.
    3. W. Wang, G. Yang, C. Evrim, A. Terzis, R. Helmig, and X. Chu, “An assessment of turbulence transportation near regular and random permeable interfaces,” Physics of Fluids, vol. 33, Art. no. 11, Nov. 2021, doi: 10.1063/5.0069311.

Data and software publications PN 1-5 and PN 1-5 (II)

  1. E. Coltman, M. Schneider, and R. Helmig, “Data-Driven Scale Bridging Parametrizations with Metrics: Dispersive Transport.” 2023.
  2. E. Coltman, M. Schneider, and R. Helmig, “A DuMux Framework for Data-Driven Multi-Scale Parametrizations.” 2023.
  3. Y. Wang et al., “DuMux 3.5.0.” Zenodo, 2022. doi: 10.5281/ZENODO.6606582.
  4. J. Hannss, “Averaged Analysis of Pore Scale Dynamics via Closure Problems.” Nov. 2021.
  5. K. Weishaupt et al., “DuMux 3.3.0.” Zenodo, 2020. doi: 10.5281/ZENODO.4271486.
  6. E. Coltman et al., “DuMuX 3.2.0.” Zenodo, 2020. doi: 10.5281/ZENODO.3784768.
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