venturi

Venturi refers to the Venturi effect, a principle in fluid dynamics describing a drop in fluid pressure that occurs when a liquid or gas flows through a constricted section of pipe. The effect is named after Giovanni Battista Venturi, an Italian physicist who described the phenomenon in 1797.

In a steady, incompressible flow, the conservation of mass requires that the product of cross-sectional area and flow velocity remains constant (A1 v1 = A2 v2). As the streamlines pass through the reduced area, velocity increases at the throat and static pressure falls, according to Bernoulli's principle. The pressure drop between the upstream section and the throat enables flow rate measurement in a device called a Venturi meter, which has a converging inlet, a narrow throat, and a gradually expanding outlet to recover pressure.

Applications include measurement of water and gas flows, fuel injection systems, aspiration and carburetors, spray nozzles, and pollution-control devices such as Venturi scrubbers. The principle is also used in laboratory equipment and in aspirators to generate vacuum. The Venturi effect is valued for having no moving parts and for its robustness in various fluid-handling tasks.

Limitations include the assumptions of steady, incompressible, and inviscid flow; real fluids exhibit viscosity and compressibility effects, especially at high speeds. Calibration and Reynolds number affect accuracy. The Venturi concept underpins many nozzles and diffusers and remains a fundamental example in fluid dynamics, illustrating how constricted flow alters velocity and pressure.

In addition to the scientific concept, "Venturi" appears in other contexts, including Venturi Automobiles, a French electric car manufacturer, and as a surname.