Research Project AX3

Exchange Processes at the Soil-Atmosphere Interface: Modelling and Numerical Analysis

Publications

Publications in scientific journals

  1. (Journal-) Articles

    1. Heck, K., Coltman, E., Schneider, J., & Helmig, R. (2020). Influence of Radiation on Evaporation Rates: A Numerical Analysis. Water Resources Research, 56(10), Article 10. https://doi.org/10.1029/2020wr027332
    2. Coltman, E., Lipp, M., Vescovini, A., & Helmig, R. (2020). Obstacles, Interfacial Forms, and Turbulence: A Numerical Analysis of Soil--Water Evaporation Across Different Interfaces. Transport in Porous Media. https://doi.org/10.1007/s11242-020-01445-6
    3. Yang, G., Coltman, E., Weishaupt, K., Terzis, A., Helmig, R., & Weigand, B. (2019). On the Beavers--Joseph Interface Condition for Non-parallel Coupled Channel Flow over a Porous Structure at High Reynolds Numbers. Transport in Porous Media. https://doi.org/10.1007/s11242-019-01255-5

Research

About this project

An understanding of the flow and transport processes occurring at the interface and between porous medium and turbulent free-flow domains is necessary when evaluating fluxes across a soil-atmosphere interface. The flow dynamics close to the surface in each domain exhibit a strong coupling to each other, where the coupling often depends on characteristics of the interface. In order to evaluate these coupled processes, an understanding of the underlying flow concepts is imperative. Within this project, exchanges at the Soil-atmosphere interface are studied, and the effects of turbulence, interface roughness, non-isothermal, and compositional flow dynamics are all investigated. Coupled REV scale two domain models are used for a detailed investigation of interface dynamics, and reduced 1D models at a larger lysimeter/field scale are used in comparison. In addition to numerical investigations, experimental work at both a laboratory scale and a lysimeter/field scale are performed. Further extensions include the transport of Isotopes, Gases, and pesticides in the subsurface in order to address further closely related applications.

Overveiew of the coupled dynamics at the soil-atmosphere interface.
Coupled dynamics at the soil-atmosphere interface.
Temperature and water vapor conditions in the near surface under different interface conditions.
Temperature and water vapor conditions in the near surface under different interface conditions.

Results

Each processes in question has been analyzed both numerically and experimentally in controlled configurations. Evaporation under the influence of surface roughness, non-flat topology, and radiation were analyzed and major influences where identified. In addition, evaluations of gas transport were performed to find that not only do diffusive dynamics play a role, but wind induced horizontal fluxes in the soil can have a high influence on gas transport in the soil. However, these detailed analyses are computationally demanding and are therefore not suitable to be used on the field scale. The project is working now to incorporate the necessary process complexity in field scale models in order to make better predictions at larger scales. 

This has begun with an analysis of water isotopologue transport in the subsurface. Here, two model concepts at different scales, a large scale resistance function based model, and a detailed coupled two domain model have been used to compare the descritpion of evaporation and transport dynamics with detailed experimental data. Further, efforts are also being made to compensate for the data-poor issues at larger scales, where limited environmental monitoring is available at the area of interest, the near surface.

Averaged PIV results from a coupled wind tunnel and soil tank experiment held at the University of Colorado Boulder.
Averaged PIV results from a coupled wind tunnel and soil tank experiment held at the University of Colorado Boulder.

Contact

This picture showsRainer Helmig
Prof. Dr.-Ing.

Rainer Helmig

Spokesman, Principal Investigator, Research Projects A02 and C02, Central Project Z

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