Flow Through an Orifice

Experiment has shown that when an orifice is made in the thin wall of a ve el containing a fluid, the fluid vein is constricted just outside the ve el, so that the actual fluid section is only ab. 62 per cent of the area of the hole in a dense fluid like water, and ab. 80 per cent in a tenuous one. A conoidal nozzle, properly shaped to the profile of the vena contract a, will give the full rendition of the area of its least section. This investigation is due to Eytelwein.