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| Critical Velocity |
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Critical velocity is the velocity of a liquid flow upto which its flow is
streamlined and after which its flow becomes turbulent. The critical
velocity depends on coefficient of viscosity 'h',
density of the liquid 'r', and radius of the tube
(r). Using the methods of dimensions, one can show that  where k is constant of proportionality |
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| The Reynolds number is a pure number that determines the nature of flow through a pipe. The critical velocity 'VC' is given by |
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| If the value of Reynolds Number NR lies between 0 to 2000, the flow of liquid is streamline or laminar (the layers of liquid glide or slip over one another like sheets or laminar). If the value of NR is greater than 3000, the flow is turbulent. For values inbetween, the flow is not steady and changes from one to another. |
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