Transport and deposition of spray droplets above and within a soybean canopy
Rhee, Joong-Yong
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Permalink
https://hdl.handle.net/2142/20200
Description
Title
Transport and deposition of spray droplets above and within a soybean canopy
Author(s)
Rhee, Joong-Yong
Issue Date
1991
Doctoral Committee Chair(s)
Bode, Loren E.
Department of Study
Agricultural and Biological Engineering
Discipline
Agricultural Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Agricultural
Language
eng
Abstract
Chemical application is the most effective and feasible method of pest control. However, the process of transport and deposition of spray droplets during application are not fully understood. Particularly, the effect of turbulence on spray transport and deposition is not clear.
The goal of this research was to develop a spray transport and deposition model that considers the effect of turbulence above and within a plant canopy. A Random Walk model which includes droplet evaporation and high initial droplet velocity and entrained air flow was used for the transport and deposition model. Data on turbulent wind velocities in a soybean field and droplet characteristics from a XR8002 flat-fan nozzle were collected, analyzed and used as an input for the model. Also, a new Random Walk model was proposed which considers skewness of turbulent velocity in the z-direction. Data for verification of the model was collected in a soybean field using water sensitive cards and analyzed by a machine vision system.
A simple Markov chain that includes Reynolds stress, displayed the best performance for mass conservation among the models that were tried. The developed model showed reasonable predictions for spray transport but deposition in top region of the canopy seemed to be overestimated.
Turbulence of air flow within and above a soybean canopy were measured and modeled as simple linear equation. Also, the data shows the possibility of a transition height above the canopy where the existence of the canopy affects turbulence characteristics.
Sensitivity analysis of the transport model indicated that 150 microns is a critical droplet diameter which balances droplet coverage and evaporation loss.
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