4

= 18,927 x ———-5—- = 69.8 cm/sec 7r(20.32 — 8.225 )

2. Find n from the slope of the 100—6 rpm curve in Fig. 5-48:

3. Find the shear rate at the wall of the hole from Equation 5-45:

3x0.22 12.1

4. Determine the effective viscosity at 151 sec 1. From Fig. 5 -48, r at 151 sec"1 = 64 dynes/cm2:

To show the importance of evaluating n at the shear rate prevailing at the wall of the hole in annular calculations, suppose the above calculations were made with the value of n given by the 600 and 300 rpm readings, i.e., n -=

0 0

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