Engineering Undergrads See X-ray Science from the Inside at GSECARS

A group of undergraduate students participating in a National Science Foundation (NSF) Research Experience for Undergraduates (REU) program, recently performed a series of synchrotron x-ray tomography experiments at the GeoSoilEnviroCARS beamline 13-BM at the APS, in collaboration with Mark Rivers (University of Chicago). This REU program, "Tomography in Civil and Environmental Engineering," is directed by Clinton S. Willson of the Civil and Environmental Engineering Department at Louisiana State University (LSU). The NSF sponsors the REU program in an effort to support active research participation by undergraduate students in any of the areas of that the NSF funds.

Three experiments were conducted. Amy Grove, a senior Civil Engineering major at Cornell University, used the 13-BM tomography station to image cores extracted from several sediment/reactive barrier systems that are part of a pilot-scale study being conducted at the University of New Hampshire. This study is being funded by the Cooperative Institute for Coastal and Estuarine Environmental Technology and the Hazardous Substance Research Center South/Southwest. The photo below shows Grove aligning one of her sediment/barrier cores prior to imaging at the 13-BM beamline.

Photo of Sarah Hunt

Sarah Hunt, a senior Civil and Environmental Engineering major at Washington State University, imaged a number of unconsolidated sand systems for a research project investigating the impact of pore structure on drainage characteristics. This project is part of an ongoing collaborative project with Allen Reed, a research scientist at the Naval Research Laboratory, Stennis Space Center, Mississippi.

Rob Stacey, a senior Civil and Environmental Engineering major at the University of Vermont, used the tomography station to investigate the entrapment of non-wetting phase fluids in porous media systems. Rob's project is in support of Willson's project, "Collaborative Research: Pore-scale Measurement and Modeling of Porous Media Systems," funded through the NSF Hydrological Sciences Division. Co-principal investigator on this project is Markus Hilpert from the Department of Geography and Environmental Engineering at Johns Hopkins University.

The figures below, obtained from one of Stacey's experiments at the GSECARS tomography beamline, demonstrate how one can use the tomography system to look at the pore-scale processes that are responsible for the trapping of non-wetting fluids in porous media. These high-quality images lead to a better understanding of the impact of pore structure on the distribution of multiphase fluids. Applications include remediation of non-aqueous phase liquids and improved oil recovery. Details of these and other projects that were part of the REU program can be found at www.cee.lsu.edu/~reu.

- Clint Willson (LSU)

Left: Solid (green) and void (blue) phases in an unconsolidated sand system; middle: the void space (blue) in the system; right: the entrapped non-wetting fluid distribution within that void space.
Fig. 1. Left: Solid (green) and void (blue) phases in an unconsolidated sand system; middle: the void space (blue) in the system; right: the entrapped non-wetting fluid distribution within that void space.