%0 Journal Article %1 chen2021nonuniqueness %A Chen, Yongqiang %A Steeb, Holger %A Erfani, Hamidreza %A Karadimitriou, Nikolaos K %A Walczak, Monika S %A Ruf, Matthias %A Lee, Dongwon %A An, Senyou %A Hasan, Sharul %A Connolley, Thomas %A others, %D 2021 %I American Association for the Advancement of Science %J Science Advances %K PN1-4 PN1 EXC2075 selected %N 52 %P eabj0960 %R 10.1126/sciadv.abj0960 %T Nonuniqueness of hydrodynamic dispersion revealed using fast 4D synchrotron x-ray imaging %U https://www.science.org/doi/10.1126/sciadv.abj0960 %V 7 %X Experimental and field studies reported a significant discrepancy between the cleanup and contamination time scales, while its cause is not yet addressed. Using high-resolution fast synchrotron x-ray computed tomography, we characterized the solute transport in a fully saturated sand packing for both contamination and cleanup processes at similar hydrodynamic conditions. The discrepancy in the time scales has been demonstrated by the nonuniqueness of hydrodynamic dispersion coefficient versus injection rate (Péclet number). Observations show that in the mixed advection-diffusion regime, the hydrodynamic dispersion coefficient of cleanup is significantly larger than that of the contamination process. This nonuniqueness has been attributed to the concentration-dependent diffusion coefficient during the cocurrent and countercurrent advection and diffusion, present in contamination and cleanup processes. The new findings enhance our fundamental understanding of transport processes and improve our capability to estimate the transport time scales of chemicals or pollution in geological and engineering systems.

@article{chen2021nonuniqueness, abstract = {Experimental and field studies reported a significant discrepancy between the cleanup and contamination time scales, while its cause is not yet addressed. Using high-resolution fast synchrotron x-ray computed tomography, we characterized the solute transport in a fully saturated sand packing for both contamination and cleanup processes at similar hydrodynamic conditions. The discrepancy in the time scales has been demonstrated by the nonuniqueness of hydrodynamic dispersion coefficient versus injection rate (Péclet number). Observations show that in the mixed advection-diffusion regime, the hydrodynamic dispersion coefficient of cleanup is significantly larger than that of the contamination process. This nonuniqueness has been attributed to the concentration-dependent diffusion coefficient during the cocurrent and countercurrent advection and diffusion, present in contamination and cleanup processes. The new findings enhance our fundamental understanding of transport processes and improve our capability to estimate the transport time scales of chemicals or pollution in geological and engineering systems.}, added-at = {2024-03-26T11:56:15.000+0100}, author = {Chen, Yongqiang and Steeb, Holger and Erfani, Hamidreza and Karadimitriou, Nikolaos K and Walczak, Monika S and Ruf, Matthias and Lee, Dongwon and An, Senyou and Hasan, Sharul and Connolley, Thomas and others}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/289d2f9e9ef0f037858162febe8962fe9/exc2075}, doi = {10.1126/sciadv.abj0960}, interhash = {8dcc27334b212495b5264c90ca289e59}, intrahash = {89d2f9e9ef0f037858162febe8962fe9}, journal = {Science Advances}, keywords = {PN1-4 PN1 EXC2075 selected}, number = 52, pages = {eabj0960}, publisher = {American Association for the Advancement of Science}, timestamp = {2024-03-26T11:56:15.000+0100}, title = {Nonuniqueness of hydrodynamic dispersion revealed using fast 4D synchrotron x-ray imaging}, url = {https://www.science.org/doi/10.1126/sciadv.abj0960}, volume = 7, year = 2021 }