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【Objective】 The Venlo-type greenhouse is commonly used in commercial horticulture due to its efficient space utilization and superior light transmission. This study investigates the impact of spire width on microclimate within such greenhouses under natural ventilation conditions. 【Method】 The study focused on multi-span glass greenhouses. We used experimental measurement and CFD modelling to simulate the variations in temperature and airflow in the greenhouse for various spire widths: 3.2 m JD3.2, 3.6 m JD3.6 and 4 m JD4 under natural ventilation conditions when the outdoor wind speed was 0 and 1 m/s, respectively. 【Result】 ① Comparing with measured temperature at different sampling points in the greenhouse reveals that the relative error of the simulated temperature ranged from 0.2% to 3.3%, ② Spire width had a significant effect on temperature distribution in the greenhouse. In particular, temperature increased upward in the greenhouses with the JD3.2 spire, while, in contrast, temperature increased downward in the greenhouses with the JD3.6 spire. ③ Regardless of the outdoor wind speed, greenhouses with JD3.2 spire had the best heat removal efficiency. The heat removal efficiency of JD3.6 and JD4 spire and the associated temperature distribution in the greenhouses was better when the outdoor speed was 0 m/s than when the outdoor wind speed was 1 m/s. 【Conclusion】 For all spire widths we compared under different working conditions, the greenhouse with JD3.2 spire work best for ventilating and cooling the greenhouse.

Water jet scouring technology is extensively applied in marine engineering, harbor maintenance, river training, and various other fields, showcasing a broad spectrum of potential applications. However, achieving a comprehensive understanding of the transient sand scouring characteristics of water jets remains challenging due to the inherent complexity of the coupled flow structure involving submerged jets and environmental fluids, along with the intricate dynamics of two-phase flow. This study, rooted in numerical simulation and experimental validation, introduces pulse characteristics into a submerged jet. A thorough investigation is conducted to explore the transient sand scouring characteristics and sand transport laws of the submerged jet under diverse working conditions. The results of this study revealed that the main reason for the asymmetry of the sand pit morphology is not the non-uniform distribution of sand grains, but more likely caused by turbulence effects. Simultaneously, within the initial 0.25 s of the pulse cycle, suspended sediment resulting from the pulsed jet in the preceding cycle gradually transports to the dune and its surrounding areas. Subsequently, from 0.25 s to 0.5 s, sediment on both sides of the pit's bottom undergoes movement and amalgamation with the sediment that remained unsettled during the previous cycle. The findings reveal that higher jet velocities significantly enhance sediment suspension, migration, and redeposition, leading to deeper erosion and the rapid formation of the sand pit's outline within 2 s. Additionally, the jet velocity and the impact distance are identified as critical factors influencing erosion depth and sediment dynamics. These insights advance the understanding of erosion mechanisms driven by pulsed jets, highlighting their impact on sediment transport processes. The research findings provide important guidance for dredging and ocean engineering fields and offer a theoretical basis for improving the understanding of submerged jet scouring mechanisms. [ABSTRACT FROM AUTHOR]