General Medical Information

Orifice Flow

Thomas V. Mccaffrey

When gas flows through a conduit with localized constriction, orifice flow can occur. Flow through an orifice has a nonlinear pressure-flow relation. The pressure to produce flow through an orifice depends on the hydraulic cross-section of the orifice. An orifice smaller than the rest of the lumen determines the resistance of the whole conduit. The orifice is a flow-limiting segment and largely determines the resistance of the airway. Orifice flow can occur physiologically within the nasal valve area. This leads to the observation that the flow-limiting segment of the nasal airway occurs in the region of the nasal valve.