Study on Numerical Simulation of Interference Infiltration Characteristic in Film Hole Irrigation
|School||Northwest University of Science and Technology|
|Course||Agricultural Soil and Water Engineering|
|Keywords||Film hole irrigation VG model Irrigation technology elements Numerical Simulation Simplified model|
This paper summarizes the inspection and analysis of domestic and foreign film hole irrigation theory and technology research results, based on a theoretical analysis of laboratory experiments and numerical simulations combine to numerical simulation and experimental verification based technology roadmap. To soil water dynamics theory, established under film hole irrigation soil water movement model to study the conditions under film hole irrigation water distribution and wetting infiltration. Through research come to the following findings: (1) high-speed centrifuges used in the test loam and sandy loam soil moisture under different density characteristic curves were measured using the horizontal soil column Determination sorptivety unsaturated soil diffusivity, According to both the measured data, the use of RETC software parameters were fitted to obtain the relevant parameters of the VG model values, indicating that the model can be well characterized VG test soil moisture characteristic curve. (2) based on soil water dynamics equation, the establishment of three-dimensional film hole irrigation soil water movement model and boundary conditions, the use of SWMS-3D software solution; through multiple sets of orthogonal film hole interior, measured cumulative infiltration under film hole water infiltration and soil moisture dynamics change process, access and distribution of soil water movement during the test data. Using the model of the membrane hole irrigation water distribution and soil moist body changes cumulative infiltration is simulated and measured values ??will simulate a comparative analysis, the results showed that: Analog basically consistent with the experimental values, indicating that the proposed model and algorithms can be used in film hole irrigation infiltration and wetting characteristics of the analysis. (3) use the model to simulate a variety of combinations of soil under different irrigation technology elements wetting soil water distribution and variation of infiltration, irrigation quota come under the same conditions, the initial moisture content of soil moisture distribution has some influence, However, the shape of the soil moist little effect on the membrane pore weak influence cumulative infiltration, irrigation water depth on soil moisture wetting weak influence on the film hole cumulative infiltration was less affected; soil texture, bulk density on soil water distribution significant effects on the membrane pores cumulative infiltration greater impact; membrane pore diameter distribution of soil moisture has little effect on the membrane pore cumulative infiltration great influence; film hole spacing on soil moisture influence the shape of the body relatively moist large amount of influence on the film hole infiltration smaller; open porosity of the membrane holes inside the control area, the average infiltration depth of impact; film hole irrigation project therefore time to consider the design of initial soil moisture and irrigation water depth of impact, and key consideration under different soil bulk density and pore diameter and the opening rate for field irrigation effects. (4) According to the numerical simulation data, create a test Alaska Krakow infiltration coefficient formula k, infiltration index α and the membrane pore diameter D and the opening ratio ρ between the simplified model, by fitting the show: infiltration coefficient k with a linear relationship with the opening rate of infiltration index α ρ into a linear relationship. Through laboratory experiments and literature have been validated on the model, the results showed that: the model calculated and measured values ??of the relative deviation is small, indicating that the model can effectively describe the point source infiltration under film hole irrigation law.