The phenomenon describing decreased pressure at a stenosis due to increased velocity is known as what?

• A. Bernoulli effect
• B. Energy balance
• C. Poiseuille's law
• D. Continuity equation

Answer: (A)

In a stenosis, the cross-sectional area shrinks, so the fluid must speed up to keep the flow rate the same. As velocity rises, static pressure falls according to Bernoulli's principle, which states that for steady, incompressible flow along a streamline, P + 1/2 ρ v^2 is constant. This is why you see lower pressure at the narrow point even though the flow is faster. The continuity equation explains why velocity increases in the constriction, but it’s Bernoulli’s relationship between velocity and pressure that describes the accompanying pressure drop. Poiseuille’s law deals with viscous resistance and overall pressure drop in laminar tubes, not the specific velocity–pressure trade-off at a constriction, and energy balance is a broader framework rather than the specific linkage here.