Experimental and numerical characterization of the vortex zones along a labyrinth milli-channel used in drip irrigation

•Mixing analysis is a crucial issue for micro-irrigation to avoid drippers clogging.•Characterization of the flow in labyrinth micro-channels is an important step to understand the clogging phenomena and mixing properties.•2D-2C Micro-PIV and the RSM model are well-adapted tools which allow to characterize and analyse the flow in the labyrinth micro-channels.•Mixing time is analysed by the ratio k/ϵ and allows to identify the region more sensitive to particle deposit.•The vortex identification techniques, as the λ and Q criteria, allow to identify the vortex zone size and position. These vortices are responible of drippers clogging. The labyrinth-channel is largely used in dripper systems. The baffles play an important role to generate the head losses and induce the flow regulation on the drip irrigation network. But they also develop vorticity regions where the velocity is low or zero. These vorticity regions promote the deposition of particles or other biochemical development causing dripper clogging. The flow in the dripper labyrinth-channel must be described to analyze dripper clogging sensibility which drastically reduces its performance. This characterization is performed experimentally using the micro-particle-image-velocimetry (Micro - PIV) method, and numerically using the RSM Simulation. In this study, Micro-PIV experiments allow to analyze the flow in ten-pattern repeating baffles which reproduce the micro-irrigation dripper. The cross section is equal to 1 mm2 and the inlet Reynolds number varies from 345 to 690. The present study first introduces a global analysis of the flow through the mean velocity modulus, the Reynolds stresses u′2¯,v′2¯ and u′v′¯ and the turbulence Reynolds number. Then, results for the mean strain rate and the mean spanwise vorticity are presented and discussed. Next, advanced methods of vortex detection are introduced and analyzed to better distinguish the vortex zones and to determine the vortex sizes. Furthermore, the numerical model is used to validate and analyze in a more detailed way the experimental results obtained by Micro-PIV.