Effects of flow path boundary optimizations on particle transport in drip irrigation emitters

Abstract

Abstract A modified digital particle image velocimetry (DPIV) was used to test particles' moving characteristics in cylindrical fractal M‐geometries flow paths with three optimized boundaries. Taken the vorticity and characteristics of streamlines distribution in the central area and the velocity field near the boundary into consideration, it was found that the fractal M‐type flow path would be optimized with a design such that the radius of an arc in tooth‐root facing‐water zone, tooth‐tip backing‐water zone and facing‐water zone was half width of the flow path. Moreover, the radius of the arc in the tooth‐root backing‐water zone was desired to be the same with the width of the flow path. This optimization was attributed to two reasons. Firstly, with a large radius arc in the tooth‐tip backing‐water zone and facing‐water zone, the velocity in the central domain and near boundary area was improved. And the following performance of particles near the boundary was suppressed. Secondly, adoption of a small arc in the tooth‐root facing‐water zone could improve the velocity, vorticity and self‐cleaning capability near wall. In conclusion, when optimizing the boundary, the distribution characteristics of vortices should be fully considered to enhance vortices development in the flow path. Copyright © 2016 John Wiley & Sons, Ltd.