Answer: Turbulent, viscous, or compressible flows.
- A Turbulent, viscous, or compressible flows
- B Slow, steady laminar flows of an ideal incompressible fluid
- C Flows occurring at a uniformly low absolute pressure
- D Flows confined to perfectly horizontal pipes of constant area
Correct answer: A. Turbulent, viscous, or compressible flows
Explanation: Bernoulli's equation applies to ideal fluid flow: inviscid, incompressible, steady, and irrotational (streamline). It fails for turbulent flow, viscous fluids, or compressible gases at high speeds.
Since the same volume of fluid must pass every cross-section per second (continuity), the fluid speeds up where the pipe narrows; Bernoulli's equation then says this faster-moving fluid has lower pressure - the principle behind a venturi meter and an aircraft wing's lift.
Concept context
Pressure, buoyancy, Bernoulli equation, viscosity, and surface tension.