After rising a short distance , the smooth column of smoke from a cigarette break ups into an irregular and random pattern. In a similar fashion , a stream of fluid flowing past an obstacles break ups into eddies and vortices which give the flow irregular velocity components transverse to the flow direction. Other examples include the waves left in water by moving ships, the sound produced by whistling and by wind instruments . These examples are the results of

• A. Laminar flow of air
• B. Streamline flow of air
• C. Turbulent flow of air
• D. Viscous flow at low speed