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LAMINAR AND TURBULENT FLOW | Up
Thermodynamics Heat Transfer and Fluid Flow Volume 3 of 3 | Next
Average (Bulk) Velocity |
LAMINAR AND TURBULENT FLOW
Fluid Flow
Flow Velocity Profiles
Not all fluid particles travel at the same velocity within a pipe. The shape of the velocity curve
(the velocity profile across any given section of the pipe) depends upon whether the flow is
laminar or turbulent. If the flow in a pipe is laminar, the velocity distribution at a cross section
will be parabolic in shape with the maximum velocity at the center being about twice the average
velocity in the pipe. In turbulent flow, a fairly flat velocity distribution exists across the section
of pipe, with the result that the entire fluid flows at a given single value. Figure 5 helps illustrate
the above ideas. The velocity of the fluid in contact with the pipe wall is essentially zero and
increases the further away from the wall.
Figure 5 Laminar and Turbulent Flow Velocity Profiles
Note from Figure 5 that the velocity profile depends upon the surface condition of the pipe wall.
A smoother wall results in a more uniform velocity profile than a rough pipe wall.
HT-03
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