CFD simulation and experimental study of the irrigation performance of new ebb-and-flow soilless cultivation troughs

Irrigation water savings constitute an important incentive for sustainable agricultural development. Ebb-and -flow irrigation provides prominent water-saving advantages in regard to the irrigation of horticultural crops. In this study, two new ebb-and-flow soilless cultivation troughs, i.e., T-and U-type troughs, were designed based on available ebb-and-flow cultivation troughs to further improve the water use efficiency. They could be divided into substrate and water supply areas by convex separating plates. The long walls of the troughs were inclined and curved. To study the performance of these new troughs, water supply and water retention processes were analyzed using computational fluid dynamics (CFD) models. A trough with an inverted triangular profile configuration was used as the control group (CK). It was found that the water supply time consumption of the U -type troughs was the lowest, accounting for 34.48% of that of the CK troughs, and the rate of the T-type troughs was the second lowest, accounting for 55.7% of that of the CK troughs; the variation in the water retention process was negligible, at<0.5%. In addition, field experiments indicated that the U-type troughs supplied water at the highest rate and exhibited a high substrate water content, and it was determined that the U-type troughs achieved the highest irrigation efficiency, which was 1.38-1.60 times higher than that of the CK troughs, and the lowest energy consumption, accounting for 18.57%-20.28% of that of the CK troughs. Moreover, cultivation trials demonstrated that the two newly designed cultivation troughs were better than the CK trough. Conse-quently, the U-type cultivation trough was found to be the best choice. This study provides a theoretical basis for the ebb-and-flow soilless cultivation of horticultural crops and introduces new products to improve the irrigation water use efficiency and reduce energy consumption.