Development of a portable vertical wind tunnel for field use

Abstract: Accurate measurement of the aerodynamic properties of particles is essential for the calibration of coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) models. Some properties of biological particles, such as moisture content and shape, can change over time, affecting their aerodynamic behaviour. To enable field measurements of biological particles, a portable vertical wind tunnel (VWT) was developed using 3D-printed ducting, a battery-powered leaf blower, and a clear polycarbonate test section. This study presents the design, construction, experimental testing, and modelling of the VWT. The terminal velocity and drag coefficient of a plastic sphere were measured with the VWT and used to calibrate one-way and two-way coupled CFD-DEM models. The results indicated that two-way coupled models can more accurately predict particle behaviour compared to one-way coupled models for measurements taken with the VWT. The portable VWT allows for field measurements of aerodynamic properties, enhancing the fidelity of coupled CFD-DEM simulations relevant to agricultural machinery. Keywords: Experimental methods, Discrete element method, computational fluid mechanics, 3D printing