Distinguish between streamline and turbulent flow, and state what decides which occurs.

In streamline flow every particle passing a given point follows the same path with the same velocity, and the layers slide smoothly over one another. In turbulent flow the motion is irregular and eddies form. Reynolds number decides which occurs: flow is streamline below about 2,000 and turbulent above about 3,000.

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Explanation

Reynolds number depends on the density, speed, dimension and viscosity of the fluid.