The Effect of Submerged and Emergent, Highly Flexible and Rigid Macrophyte Canopy Patches on Flow and Mass Transport

Cornell University, Ithaca NY

Investigators

Abstract

PROPOSAL NO.: CTS-0626164 PRINCIPAL INVESTIGATOR: EDWIN A. COWEN INSTITUTION: CORNELL UNIVERSITY THE EFFECT OF SUBMERGED AND EMERGENT, HIGHLY FLEXIBLE AND RIGID MACROPHYTE CANOPY PATCHES ON FLOW AND MASS TRANSPORT This grant provides funding to perform a series of carefully controlled experimental studies on the effects of aquatic macrophyte canopy patches on low-speed flows. The literature on the effects of terrestrial and aquatic vegetation on flow is becoming quite rich but there is a significant gap in the aquatic plant literature on the effects of heterogeneous canopies in low-speed flows and for the effects of highly flexible macrophtyes in general. The investigators will collect a canonical experimental data set documenting the effects of highly flexible macrophyte canopies and heterogenous macrophyte patches on low-speed flow and mass transport. A secondary goal is to extend and investigate the ability of existing turbulence closure schemes to capture these effects. The experiments will be conducted using two species of live macrophytes. The macrophytes will be placed in patches of increasing complexity in the all glass test section of a wide open-channel flume. State of the art quantitative imaging techniques will be used to measure the turbulent velocity characteristics, including the directly calculated turbulent dissipation, as well as the transport and dispersion of fluorescent tracers. Proposed modifications to turbulence closure models will be the starting point for investigating the ability of models to capture the turbulent kinetic energy budget. Competing numerical models of canopy flow that perform equally well in uniform aquatic canopies will be tested against this novel heterogeneous data set. The collected data set will fill critical gaps in our understanding of aquatic plant-flow interaction. It is important to work with live plants, as field biologists monitor macrophyte communities using metrics that do not lend themselves to scaling with simulated plant model results. The tested turbulence closure models will allow the development of computational tools capable of forecasting transport in natural environments dominated by both highly flexible and heterogeneous plant canopy patches - environments such as lakes of all scales, salt marshes, estuaries and coastal embayments and terrestrial flows as well. The project will lead to an interdisciplinary Ph.D. for a talented female student who will work with the PI to develop laboratory experiences for an introductory fluid mechanics course and to host weeklong projects for a program targeting high-school women interested in science and engineering.