Question

Example of turbulent flow?

(a) Smoking rises from cigarette

(b) Flow on a symmetric airfoil

(c) Laminar flow

(d) Turbulent flow on the airfoil

I got this question in final exam.

The origin of the question is Turbulent Flow topic in chapter Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Right option is (a) Smoking rises from cigarette

To explain I would say: Smoke rising from a cigarette is mostly turbulent flow. However, for the first few centimeters, the flow is laminar. The smoke plume becomes turbulent as its Reynolds number increases, due to its flow velocity and the characteristic length.