The viscosity of liquids is measured with a capillary viscometer, in which a laminar flow is maintained in a small diameter tube, and the pressure drop and flow rate are measured. If the flow is fully developed, then Eq. 9-13 can be used to calculate the liquid viscosity. However, entrance effects often are present. Consider the flow of a liquid (SG = 0.92) through a tube 450-mm long and 0.75-mm in diameter. A flow of 1 cm3/s is obtained when the pressure drop is 65 kPa. Determine:
a. the viscosity if the flow is fully developed (in Ns/m2)
b. the viscosity if the pressure drop in the entrance length is twice that for the same length of fully developed flow (in N·s/m2).