Drip irrigation supplies water directly near the roots of plants. At the heart of each dripper is a very small labyrinth channel containing repeated bends and obstacles. Its geometry determines the relationship between supply pressure and water volumetric flow.
Because the labyrinth is produced by injection moulding, manufacturing prototypes for many geometry variants is expensive. FlowMotion therefore combined measurements and CFD to develop a numerical design method for these small flow passages.
The flow through the labyrinth contains strong accelerations, pressure losses and recirculation zones generated by the repeated geometric changes. CFD made the local velocity and static-pressure fields visible and showed how individual geometric features contributed to the overall pressure drop.
Experimental measurements were used to establish and validate the relationship between pressure and volumetric flow. Once validated, the numerical model could be used to evaluate new labyrinth geometries before an injection mould was manufactured.
The resulting design tool reduced the dependence on trial-and-error prototyping and provided direct physical insight into the hydraulic behaviour of the dripper.
