Canopy edge flow: A momentum balance analysis
Citations Over TimeTop 25% of 2015 papers
Abstract
Abstract Canopy flow models are often dedicated to ideal, infinite, homogenous systems. However, real canopy systems have physical boundaries, where the flow enters and leaves patches of vegetation, generating a complex pressure field and velocity variations. Here we focus our study on the canopy entry region by examining the terms involved in the double (space and time) averaged momentum equations and their relative contribution to the total momentum balance. The estimation of each term is made possible by particle image velocimetry (PIV) measurements in a model canopy constructed of randomly distributed thin glass plates. The instantaneous velocity fields were used to calculate the mean velocities, pressure, drag, Reynolds stresses, and dispersive stresses. It was found that within the entry region, the pressure gradient, the drag forces, and dispersive stresses are the three most significant terms that affect the balance in the streamwise momentum equation. In the vertical direction, the dispersive stresses are also significant and their contribution to the total momentum cannot be ignored. The study shows that dispersive stresses are initially formed around canopy edges; at both the entry region and the canopy top boundary. They start as a sink term, extracting momentum from the flow, and then become a source term that contributes momentum to the flow until they eventually decay at some short penetration distance into the canopy. These results reveal a new understanding on the evolution of momentum within the entry region, necessary in any closure modeling of flow in real canopies.
Related Papers
- → Effects of two contrasting canopy manipulations on growth and water use of London plane (Platanus x acerifolia) trees(2014)20 cited
- → Canopy-scale modifications of the seagrass Amphibolis griffithii in response to and recovery from light reduction(2014)4 cited
- → The response ofAcacia karrooplants to defoliation of the upper or lower canopy(1989)4 cited
- Effects of canopy structure on photosynthesis and yield in cotton(2015)
- → Extraction of canopy closures and stem diversities in winter wheat(2005)