Question

Why does laminar flow transition to turbulent flow?

a) Increase in Reynolds number
b) Decrease in fluid viscosity
c) Expansion of pipe diameter
d) Reduction in fluid velocity

Answer 1

Laminar flow transitions to turbulent flow when the Reynolds number, which is influenced by fluid density, speed, viscosity, and tube radius, increases and exceeds a critical threshold.

Step-by-step explanation:

Laminar flow transitions to turbulent flow primarily due to an increase in Reynolds number. The Reynolds number is a dimensionless parameter defined by NR = (p * v * 2r) / n, where p is the fluid density, v its speed, n its viscosity, and r the tube radius. When the Reynolds number is below about 2000, the flow is typically laminar. However, as the Reynolds number exceeds approximately 3000, the flow becomes turbulent. Obstructions, surface roughness, and flow speed can all influence this transition. In the context of blood flow, the aorta can experience turbulent flow when blood speed rises above a critical value.