Verification Case 46
PRODUCT: AFT Fathom
TITLE: FthVerify46.fth
REFERENCE: James John, William Haberman, Introduction to Fluid Mechanics, 2nd Ed., 1980, Prentice-Hall, Page 176-178, Example 6.4
FLUID: Water at 20 deg. C
ASSUMPTIONS: Use the K factors provided
RESULTS:
| Parameter | John & Haberman | AFT Fathom |
| Pressure at discharge (kPa gage) | 116 | 115.0 |
DISCUSSION:
The K factors used by John & Haberman differ from Crane's and those in the AFT Fathom library. The model therefore uses the same K factors as used in the problem solution. In the problem solution, the K factor for contraction area change is applied to the 7.5 cm pipe, while AFT Fathom applies it to the 15 cm pipe. It therefore needed to be multiplied by the area ratio squared, which is 16.
The pipe lengths between fittings were not specified, and do not affect the results. The AFT Fathom assumed pipe lengths, with the total pipe length adding up to 130 m.
Results disagree slightly because John & Haberman read friction factors from a chart, which is less accurate than AFT Fathom's correlation based method. The friction factor for the 7.5 cm pipe was determined to be 0.027 by John & Haberman, and AFT Fathom calculated it as 0.028 based on the Colebrook-White method.
The resulting 115.1 kPa (g) pressure is obtained in AFT Fathom by looking at the exit pressure from the Assigned Flow junction at J8.
Note this model uses fluid properties from the AFT Standard fluid library. The AFT Standard fluid library was updated in AFT Fathom 12, thus the AFT Fathom results will be slightly different for this verification case when compared to previous versions of AFT Fathom.
