Consider a fluid entering a circular pipe at a uniform velocity,
Consider a fluid entering a circular pipe at a uniform velocity,
1) The region from the pipe inlet to the point at which the velocity profile is fully developed is called the hydrodynamic entrance region.
2) The thickness of the boundary layer increases in the flow direction until the boundary layer reaches the center.
3) The wall shear stress is highest at the pipe inlet.
Which of the above statements are correct?
A. 1 and 2
B. 1 and 3
C. 1, 2 and 3
D. 2 and 3
Please scroll down to see the correct answer and solution guide.
Right Answer is: C
SOLUTION
Concept:
Consider a fluid entering a circular pipe at a uniform velocity,
The region from the pipe inlet to the point at which the velocity profile is fully developed is called the hydrodynamic entrance region and the length of this region is called the hydrodynamic entry length (Le)
The region beyond the entrance region in which the velocity profile is fully developed and remains unchanged is called hydrodynamically fully developed region.
The thickness of the boundary layer increases in the flow direction until the boundary layer reaches the pipe center and thus fills the entire pipe as shown in the figure.
The wall shear stress is highest at the pipe inlet where the thickness of the boundary layer is smallest and decreases gradually to the fully developed value.
