Vena contracta position estimated from numerical simulations. Three-dimensional numerical simulations of a steady flow (20 l/min) through an orifice plate with an EOA = 1.00 cm2 were performed using a computational fluid dynamics package (Fluent, ANSYS, Canonsburg, PA, USA) package. More than 106 elements were used. Turbulent flow was modelled using a standard k-ω model. The figure shows the maximum velocity along the centre of orifice from -10 cm to +10 cm. Zoomed region shows the region of vena contracta downstream of the sharp-edge orifice.