The Local losses Λ are caused by energy dissipations resulting from a greater turbulence of the current, produced by the abrupt narrowing of the section in correspondence with the couplings of the drippers, resulting in proportional to the squares of the speed of the current Vg inside the dripper. They can be expressed in the form
Λ = α * Vg 2 / (2g)
in which α is indicated a proportionality coefficient, which can be determined according to the ratio between the section of the duct and the contracted section in which the dripper is located.
Along the dispensing wings, in correspondence with the numerous connections between the emitters and the pipe, local losses are determined which, in relation to the high number of emitters arranged along the lateral, can overall become not negligible compared to the friction losses; these losses must therefore be taken into account in order to accurately estimate the total head losses.
