Numerical Simulation of Airflow and Particle Collection by Vegetative Barriers

Abstract

Vegetative barriers have the potential to mitigate particulate matter (PM) from open dust sources, including unpaved and paved roads, exposed storage piles, and agricultural sources; however, data on their effectiveness in capturing PM are limited. This study was conducted to predict the airflow and particle collection efficiency of vegetative barriers. The applicability of computational fluid dynamics (CFD) in modeling airflow around and through porous barriers was first evaluated by simulating airflow passing a porous fence (1.2 m high × 0.01 m thick, 50% porosity) using standard and realizable k -ε turbulence models in FLUENT. Predicted air velocities compared favorably with available experimental data. The CFD model was then applied to simulate airflow and particle collection by a row of trees (2.2 m high × 1.6 m wide) with characteristics similar to those of hawthorn trees. The Eulerian-Eulerian model was used to predict particle transport and collection by the tree elements. Predicted particle collection efficiencies for the trees agreed with available experimental data and ranged from less than 1% for 0.875-μm particles to approximately 32% for 15-μm particles. Results from this study indicated that numerical simulation with CFD can be used to predict particle collection efficiency of vegetative barriers and that this technique has the potential to advance research on vegetative barriers for dust control for open sources. Further work is investigating effects of the structure of vegetative barriers on particle collection.