Improving simulation accuracy of a drip irrigation tooth emitter: Simulation and verification of tooth tip fillet

Numerical simulations are a reliable and commonly used research method for optimizing the structure of toothed labyrinth channels. However, simulations often involve a physical model of the sharp angle (SA) that is inconsistent with the actual emitter, which distorts the results to a certain extent. This study investigated two tooth-tip filleting methods (constant and variable angles) with five radii (r0.02–r0.10 mm) and compared them with SA, analysing impacts on hydraulic characteristics. Results showed sharp angles widened flow channels by 22.77–22.85 % versus r0.10 mm fillets, reduced emitter flow rates by 23.66–27.94 % under each pressure gradients, and overestimated energy dissipation by 40.36–43.41 %. Internally, SA increased wake vortex areas at tooth tips, Q-criterion vortex intensity was overestimated by 27.75–45.04 %, while mean flow velocity, turbulent kinetic energy (TKE), and TKE dissipation rates were overestimated by 12.66–14.10 %, 18.84–20.59 %, and 20.52–22.42 %, respectively. TKE and dissipation rate zones were overestimated by 50.51–57.96 % and 37.55–47.84 %. Hence, when the SA physical model was used to optimise the structure of the toothed labyrinth channel, in addition to the deviation from the physical structure of the emitter, there were large deviations in the simulation calculations of the flow rate, energy dissipation, and internal hydraulic characteristics. However, the filleted-tooth tip, which was consistent with the machining accuracy of the emitter, further improved the simulation accuracy. The results provide important reference values for the optimal design of drip irrigation emitters and reducing their processing costs.