Date of Award

January 2015

Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Marcellin Zahui


This thesis will focus on rear discharge bagging performance for Rear Discharge Rear Collect (RDRC), Select Series Lawn & Garden tractors. The problem under investigation pertains to adequately transporting cut grass from the mower deck to the dedicated hopper, without the plugging of the rear discharge chute or the deck mounted chute. The most problematic weather related factors are dew and rain, with the former being the most severe. Conditions creating this problem typically occur during the spring months and when the grass is at its healthiest state.

Field research and data have been collected to gain a better understanding of any and all factors involved as well as what factors can be controlled, what factors are uncontrollable, and what factors can be held constant. Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) simulations have been conducted to aid in geometry factor identification, field data validation, and field performance predictions.

During this study, a path was identified that leveraged the airflow generated by the mower blades through the rear discharge and mower deck chutes, in moving cut grass from the mower deck to the hopper. Further development of the chutes airflow has aided in increased bagging performance and decreased plugging during tough mowing conditions. Consequently, a better understanding of the CFD and DEM models result in improvements to future model analyses.