Study On Numerical Simulation Of Interference Infiltration Characteristic In Film Hole Irrigation

This paper is based on consulting and summarizing the domestic and international film hole irrigation theory and technology, the technical route involved laboratory experiment, theoretical analysis and numerical simulation, which numerical simulation and experimental verification is the main route. Based on soil water dynamics theory, film hole irrigation soil water infiltration model is established.From the research studied above, it can be concluded that:(1) Used high-speed centrifuge to measure soil water retention curves for medium loam and sandy soil in different bulk density, the horizontal column infiltration method was used to measure the soil water diffusivity.According to both the measured data, the parameters for van Genuchten model can be obtained by using RETC software.This shows that VG model can greatly express experiment soil water retention curves.(2) Based on soil hydrodynamic equation,a 3-d soil hydrodynamic model and boundary condition is proposed for film hole irrigation,which is solved by SWMS-3D software.Through eight orthogonal tests film hole irrigation laboratory experiment,measure the film hole cumulative infiltration and dynamic water content changes of soil infiltration,we also get the water movement procession and distribution of test data.Using established model in this study, we simulate soil wetting pattern water distribution and film hole cumulative infiltration. Compared by simulated values and measured values, which have been analyzed, the results showed that the simulated values had little difference from experiment results.The model and algorithm in this paper can be used to simulate the water soil movement under film hole irrigation.(3) The soil water retention curves and infiltration capacity law in different combination is simulated by using established model.obtained conclusion that the initial water content has a certain effect on soil water distribution,has a little effect to soil water content wetting soil body and film hole cumulative infiltration;the water pressure has a distinct effect on soil water content wetting soil pattern,has a certain effect to film hole cumulative infiltration;the bulk density has a significant effect on soil water content wetting soil body,has a greater effect to film hole cumulative infiltration;the film hole diameter has a little effect on soil water distribution,has a greater effect to film hole cumulative infiltration;Film hole spacing has a greater effect on soil water content wetting soil dody,has a little effect to film hole cumulative infiltration;the opening ratio has a greater effect to cumulative infiltration of film hole control unit area;Therefore we can ignore effects of initial water content and water pressure on film hole irrigation engineering,mainly consider effects of film hole diameter and opening ratio in different bulk density.(4) According to the numerical simulation data,the relationship between the infiltration coefficient k ,the infiltration indexαof kostiakove quation and the film hole diameter D ,the opening ratioρis established.It showed that the infiltration coefficient k is linear relationship withρD0.68 and the infiltration indexαis linear relationship withρby fitting.Results of model were verified by the laboratory test and the existing literature showed that the relative deviation between the calculation value and measured value is less. The established model can effectively describe point source infiltration model for the film hole irrigation.