Which statement best describes laminar flow?

Which statement best describes laminar flow?

• A. Particles move in definite, fixed paths or streamlines
• B. Irregular flow with lack of clear streamlines
• C. Re > 2300
• D. Specific Gravity equals Viscosity

Answer: (A)

Laminar flow moves in smooth, orderly layers, with each fluid particle following a fixed path called a streamline. The motion is predictable and the layers slide past each other with little mixing, producing a smooth velocity profile (parabolic in a circular pipe for a Newtonian fluid). This calm behavior happens when viscous forces dominate and the Reynolds number is low. By contrast, turbulent flow is chaotic, with eddies and fluctuations where streamlines aren’t clearly defined. That’s why the statement describing particles moving along definite streamlines is the best description of laminar flow. The idea of irregular flow without clear streamlines points to turbulence, and a Reynolds number above a common threshold signals transition toward that turbulent regime. The notion that Specific Gravity equals Viscosity isn’t relevant to identifying laminar flow.

Laminar flow moves in smooth, orderly layers, with each fluid particle following a fixed path called a streamline. The motion is predictable and the layers slide past each other with little mixing, producing a smooth velocity profile (parabolic in a circular pipe for a Newtonian fluid). This calm behavior happens when viscous forces dominate and the Reynolds number is low. By contrast, turbulent flow is chaotic, with eddies and fluctuations where streamlines aren’t clearly defined. That’s why the statement describing particles moving along definite streamlines is the best description of laminar flow. The idea of irregular flow without clear streamlines points to turbulence, and a Reynolds number above a common threshold signals transition toward that turbulent regime. The notion that Specific Gravity equals Viscosity isn’t relevant to identifying laminar flow.