Sustained Bio-Convection in Porous Media

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

National Science Foundation ABSTRACT Proposal Number: CTS-0500466 Principal Investigator: Peter Vadasz Affiliation: Northern Arizona University Proposal Title: Sustained Bio-Convection in Porous Media SUSTAINED BIO-CONVECTION IN POROUS MEDIA The proposal was received as an unsolicited investigator-initiated submission to the Chemical and Transport Systems Division and was subsequently transferred to the Thermal Transport and Thermal Processing Program for subsequent funding. This project is a fundamental research aimed at investigating the effect of sustained bio-convection in a fluid saturated porous medium (such as soil, food, human tissue) by applying theoretical as well as experimental techniques. Bio-convection is the phenomenon of gravity driven fluid motion due to buoyancy forces resulting from density differences between the fluid and motile micro-organisms suspended in the fluid. So far effects of bio-convection in porous media received little or no attention, despite the fact that micro-organisms grow naturally in porous environments; soil, food and human tissues serve as basic examples. A major focus of our research is linked to the sustainability of the bio-convection motion. The existing work on bio-convection in both pure fluids and porous media exclude micro-organism growth during the bio-convection because the time scales concerned were very short ( between a few seconds and up to 5 minutes). However, when the question of the sustainability of this convection over long times arises, micro-organism growth has to be accounted for. If sustained bio-convection in porous media is possible it opens the avenue to investigate its impact on microbial proliferation in soil, food and human tissue, an important avenue for application of the theoretical results. Then, if bio-convection enhances microbial proliferation it may be undesirable in some cases, e.g. in food, or it might be desirable if specific micro-organisms that can be used for contaminated soil remediation will be "helped" by the bio-convection process to access contaminated regions in the soil. The research will therefore expand the existing scarce knowledge on bio-convection in porous media. The anticipated outcomes from this research are publications in journals and conferences hence disseminating the scientific results, a strong international collaboration with two teams from South Africa, and about six undergraduate students from Northern Arizona University who will be heavily involved in the project.