Explain critical speed,white water rapids,and turbulent flow.

(N/A) Critical speed: Steady flow is achieved at low flow speeds up to a limiting value,called critical speed.
Turbulent flow: In a fluid flow,if the velocity of the fluid changes erratically from point to point as well as from time to time,the flow is known as a turbulent flow. If the speed of the fluid becomes greater than the critical speed,the flow loses steadiness and becomes turbulent.
White water rapids: When a fast-flowing stream encounters rocks,small foamy whirlpool-like regions called 'white water rapids' are formed.