The laminar pipe flow example of Prob. 1.12 can be used to design a capillary viscometer [29]. If Q is the volume flow rate, L is the pipe length, and ?p is the pressure drop from entrance to exit, the theory of Chap. 6 yields a formula for viscosity:
Pipe end effects are neglected [29]. Suppose our capillary has r0 — 2 mm and L — 25 cm. The following flow rate and pressure drop data are obtained for a certain fluid:
Q, m3/h | 0.36 | 0.72 | 1.08 | 1.44 | 1.80 |
?p, kPa | 159 | 318 | 477 | 1274 | 1851 |
What is the viscosity of the fluid? Note: Only the first three points give the proper viscosity. What is peculiar about the last two points, which were measured accurately?
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Fluid Mechanics
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