Wind Machines for Frost Damage Mitigation

Abstract

Frost is a meteorological phenomenon that can cause significant damage to crops and fruit plants, leading to substantial economic losses in the agricultural sector. In 2017, spring frosts caused losses amounting to 3.3 billion euros across Europe (Lamichhane, 2021). In France, at least half of the 680 km2 of vineyards were damaged due to frost events in 2021 (Liubchenkova, 2021). Due to global warming, bud blooming tends to occur much earlier, while the probability of single frost nights in spring remains the same. Consequently, crop vulnerability increasingly coincides with the frost season. Effective mitigationmethods such as sprinkling, wind machines, and paraffin pots remain essential for preventing crop damage.
Among various mitigation methods, wind machines are potentially cost-effective and energy-efficient. However, little is known about the warming effectiveness of wind machines and the physical mechanisms behind the warming process. Therefore, the primary motivation of this thesis is to investigate whether wind machines are effective warming devices for future frost damage mitigation. However, current physical understanding of machine-inducedwarming remains limited. Experimental studies often face challenges with the coverage and resolution of measurements, which are typically insufficient to fully capture the temporal and spatial variability of machine-induced air mixing in orchards. Furthermore, there are only a few numerical studies available. The dynamic interplay between turbulent warming plumes and canopy structure, as well as the heterogeneous plant-air heat exchange in the orchard, has not been investigated numerically so far....