Search Results (4)

Accurate numerical simulation of turbulent flow within the milli-channels of drip irrigation emitters has long been a significant challenge. This paper presents a comprehensive Reynolds-Averaged Navier–Stokes (RANS) modeling-based analysis of the flow dynamics within the labyrinth milli-channel of a tooth-shaped emitter, with partial experimental validation. The objective was to assess the performances of four RANS turbulence models: RNG k-ε (RNG), Realizable k-ε (RKE), SST k-ω (SST), and baseline k-ω (BSL), alongside three near-wall treatments: scalable wall function (SWF), enhanced wall treatment (EWT), and y⁺-insensitive wall treatment (YIWT) for emitter flow analysis. The results showed that the RNG and RKE, coupled with EWT, are preferred options for predicting the flow rate—pressure loss relationship of the emitter, with relative errors of 2.08% and 1.02% in the discharge exponent and 5.66% and 7.58% in the flow rate coefficient, respectively. Although both RNG and RKE using SWF are viable for hydraulic performance prediction under high-flow rate conditions, the deviation of predicted flow rate reaches up to 25.46% under low-flow rate conditions. The SST and BSL models, which employ IYPT, captured induced vortices at channel corners; however, they underestimated emitter flow rates. Furthermore, computations using SWF failed to capture the asymptotic characteristics of flow parameters in the near-wall region, resulting in an overestimation of turbulent kinetic energy and turbulence intensity. Additionally, the magnitude of wall shear stress in the channel corners fell below the threshold required for self-cleaning, underscoring the necessity for optimizing channel structures to enhance the anti-clogging performance of the emitter. Full article

The hypothesis of this paper is that infiltration into drip irrigated soils can be described by simple spherical considerations as well as two dimensional (2D) numerical modeling. The major goal was to test a very simple model based on geometry of a sphere formulas, and compare it with elaborated numerical solutions and field experiments. Detailed analysis of soil–water infiltration under trickle regimes is shown to be pre-requisite in the search for the optimal design of system layout. Optimality and simplicity are sought by modeling a sphere for subsurface trickle/drip (SDI) and hemisphere (DI) pattern of moisture distributions during infiltration. Numerical simulations by MATLAB software were used to describe the distribution of soil water. The data produced by this simulation were successfully compared with analytical models and numerical results of Panoche clay loam. To simulate the four discharge rates (0.5, 1, 2, 3 $\frac{L}{h}$) under DI and SDI we used the input of Panoche soil properties, i.e., hydraulic conductivity function (K_θ) and soil water retention curve (ψ_θ). The resulting regression equation of numerical analysis (N) vs. spherical interpretation (S) was N = 0.97 × S − 19.1; r² = 0.98. This result exposes the novelty of the approach by showing that infiltration from a drip/trickle source can be described by simple spherical radial symmetry in addition to analytical or numerical simulations. An example of a design parameter for 3000 $\frac{{\mathrm{cm}}^3}{\mathrm{h}}$ suggested more emitters per meter laterals for SDI than for DI (100 vs. 77 unites, respectively) due to the shorter distance between SDI emitters that are required in order to maintain wetting continuity. At a discharge of around 500 $\frac{{\mathrm{cm}}^3}{\mathrm{h}}$ of three different soils’ SDI, positive pressure was detected near the orifice and it caused discharge reduction. This is a self-compensating property of SDI that regulates individual emitters according to the soil hydraulic properties. In conclusion SDI is associated with larger capital investment compared to DI, but it can be compensated by improving the water use efficiency due to increased productivity while reducing losses of water through evaporation, but this option should be investigated as part of specific research. Full article

A new Variable Rate Drip Irrigation (VRDI) emitter that monitors individual water drops was designed, built, and tested. This new emitter controllers water application directly by monitoring the volume applied in contrast to uniform drip irrigation systems that control water application indirectly by pressure compensation and operational times. Prior approaches assumed irrigation volumes based on flow rates and time and typically did not verify the applied amount of water applied at each water outlet. The new VRDI emitter self-monitors the total volume of water applied and halts the flow once the desired total water application has been achieved. This study performed a test for a new VRDI emitter design with two inner diameters of 0.11 cm and 0.12 cm and two outer diameters 0.3 cm and 0.35 cm compared to a commercial drip emitter. Laboratory tests verify that the integrated volume measurements of the VRDI system are independent of pressure. Conversely, the flow rates of the commercial pressure-compensated drip lines were not independent of pressure. These results demonstrate that this form of VRDI is technically feasible and is shown to be energy efficient, requiring lower system operating pressures than pressure-compensated lines. The VRDI system can reduce water consumption and related water costs. Full article

A synchronous optimization method for self-pressure drip irrigation pipe network system is proposed. We have generalized the optimization design problem of the system and have established the mathematical models for the simultaneous optimization design of pipeline layout and pipe diameters. A genetic algorithm based on the infeasibility degree of the solution was used to solve the model. A typical example is used to validate the presented method. The method exhibits effective performance in the case studied. Designers can use the results of this study to efficiently design self-pressurized drip irrigation network systems. Full article