3D ORCHARD CANOPY ARCHITECTURAL MODELLING FOR USE IN AIRFLOW AND DRIFT PREDICTIONS

Abstract

The current trend in studying the interaction of vegetation canopies with their environment and numerical prediction of drift is mainly based on porous media approaches. The methods involve several approximations and estimations that give the global effect of the canopies to airflow and drift without investigating the detailed local effects of the vegetation elements. These approaches also require precise estimation of certain parameters such as drag coefficient and leaf area density. To make some advances in the field and to address some of the above problems a new approach needed to be developed, where real canopy architecture was modelled and linked to a computational Fluid Dynamics (CFD) software to model airflow through the canopies. This helped to investigate the real effects of the vegetation elements on atmospheric airflow which directly affects drift and drift prediction. In this work, 3D orchard canopy architecture was modelled using a combined discrete-continuous plant growth simulation model, which considered the phenomenological plant growing behaviour and the effect of temperature. Two canopy geometries were introduced into a fluid domain and the domain was meshed. Airflow around and through the canopy was simulated using the Reynolds-averaged Navier-Stokes (RANS) equations and k-H turbulence model. The airflow simulation results agreed both qualitatively with wind tunnel validation experiment and quantitatively with previous works done in the area, ensuring the prospect of the architectural modelling for further application. It was also possible to show the detailed effects of canopy elements on airflow.