Which statement about laminar flow is true?

Which statement about laminar flow is true?

• A. Flow is disorganized.
• B. Flow travels in parallel layers with minimal mixing.
• C. Flow occurs only at high velocities.
• D. Laminar flow is the same as turbulent flow.

Answer: (B)

Laminar flow is smooth and orderly, with the fluid moving in parallel layers that slide past one another with minimal mixing. In this regime, each layer keeps its identity as it progresses, producing a predictable velocity profile (flow is fastest in the center and slower near the walls in a straight tube). This exact description—flow traveling in parallel layers with minimal mixing—makes it the correct characterization of laminar flow. In cardiovascular contexts, blood in healthy vessels tends to move in orderly streams, while turbulence creates disorganized motion with eddies and mixing, often arising when flow becomes unstable at high Reynolds numbers or due to obstructions. Laminar flow does not require high speeds; it occurs when viscous forces dominate (low to moderate Reynolds number). It is not the same as turbulent flow, which is chaotic and involves significant mixing.

Laminar flow is smooth and orderly, with the fluid moving in parallel layers that slide past one another with minimal mixing. In this regime, each layer keeps its identity as it progresses, producing a predictable velocity profile (flow is fastest in the center and slower near the walls in a straight tube). This exact description—flow traveling in parallel layers with minimal mixing—makes it the correct characterization of laminar flow. In cardiovascular contexts, blood in healthy vessels tends to move in orderly streams, while turbulence creates disorganized motion with eddies and mixing, often arising when flow becomes unstable at high Reynolds numbers or due to obstructions. Laminar flow does not require high speeds; it occurs when viscous forces dominate (low to moderate Reynolds number). It is not the same as turbulent flow, which is chaotic and involves significant mixing.