ChaosAD

ChaosAD aims at providing experimental evidence of the effects of chaotic advection on solute transport and mixing enhancement in porous media. The experimental work will be accompanied by the development of advanced numerical methods to perform an accurate model-based interpretation of the results.

Main Question:

Are the theoretical and numerical outcomes obtained in recent publications about chaotic advection and related mixing enhancement in porous media supported by experimental evidence?

Hypothesis

a)  Engineered injection/extraction protocols can be reproduced under controlled laboratory conditions and effectively lead to chaotic advection and consequently to significant mixing enhancement (i.e., more than the uncertainty of experimental and model results obtained under transient yet non-chaotic conditions).

b)  Transient flows at the boundary between fresh water and salt water can be experimentally established under controlled laboratory conditions and result in chaotic advection and consequently in significant mixing enhancement also when density effects of the different solutions are considered.

c)  Chaotic advection is able to enhance mixing both under advection and diffusion dominated regional groundwater flow and experimental evidence can be provided for conservative and for reactive tracers whose transport may also be impacted by density driven effects and/or retardation due to interphase mass transfer processes.

Specific goals

1. To build three appropriate laboratory bench scale experiment set-ups demonstrating chaotic advection flows at the Darcy scale.
2. To develop accurate non-invasive optical techniques to measure spatially distributed concentrations of different tracers to demonstrate the mixing enhancement due to chaotic advection.
3. To test if the generation of chaotic advection is limited by experimental constraints (i.e., the time for re-orienting the flow field using a pumping system, the uncertainty in the pumping rate of the system, and the uncertainty in the mean groundwater flow), to test the reproducibility of the experiments and to quantify the experimental uncertainty in the results.
4. To develop numerical methods/codes able to accurately model the experiments and to explain the experimental results considering the experimental and modeling uncertainties.
5. To test if newly developed theoretical metrics, such as the critical reaction time and the dilution index of reactive species, can be applied under chaotic advection conditions and for the interpretation of the laboratory experiments.
6. To use numerical simulations to investigate the relevance of the outcomes obtained at the laboratory scale for practical field scale scenarios.

Project Duration: 2022- February 2024

Project funding: German Research Foundation (DFG)

Project team:  Prof. Gabriele Chiogna, Dr.-Ing. Mónica Basilio Hazas, M.Sc. Carla Feistner