5. Venturi Effect

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe.

Essentially the aspect of the Venturi effect we are interested in is that;

An in compressible fluid must have an increase in velocity as it passes through a pipe section with smaller area to conserve mass flow rate according to the Bernoulli equation

In our case there is no height change so the equation becomes;

Stating that the pressure change is proportional to the squared velocity change. This is how choked flow is achieved.