Dynamics of Fluid Mixing Jerry Gollub, Haverford/Penn, DMR-0405187

1. Dynamics of Fluid MixingJerry Gollub, Haverford/Penn, DMR-0405187 • The progress of chemical reactions is determined by the stirring or mixing of separate components in solution. The product’s growth can be predicted by monitoring the “stretching field”, which measures the rate at which fluid elements are elongated by the flow. • We applied these methods to studies of reactions in the presence of chaotic mixing using fluorescence to monitor the product. • This work was published in Physical Review Letters and was also highlighted in Physics Today. Currently, we are extending our work on mixing to turbulent flows. The concentration of product (red is high) for a reacting flow subjected to chaotic mixing in a layer of fluid about 10 cm on a side. Our work shows that the mixing process is much more non-uniform than previously thought.

2. Dynamics of Fluid MixingJerry Gollub, Haverford/Penn, DMR-0405187 Impact on Education and Technology: • This project develops the research talent of undergraduates through collaborations with more experienced investigators. • As Chair of the Division of Fluid Dynamics of the American Physical Society, PI Jerry Gollub led the development of a special report for congressional and agency staff entitled 'Research in Fluid Dynamics: Meeting National Needs. • He also contributed to the NSF's Math-Science Partnerships Program for K-12 education, by helping to design workshops for program staff in collaboration with the National Research Council’s Center for Education. Velocity field of a polymer solution being mixed in a microfluidic cell in the PI’s laboratory. Small-scale fluid processing is leading to novel technological applications and scientific insights.