Page 74 - Mechanical Engineers' Handbook (Volume 4)

8 Dimensionless Numbers and Dynamic Similarity 63

Figure 19 Geometry of two-dimensional jets.

of diameter d in a large tank (d/D
0), the jet diameter would be (0.611) 1/2 0.782 times
the hole diameter, since
90 .

8 DIMENSIONLESS NUMBERS AND DYNAMIC SIMILARITY
Dimensionless numbers are commonly used to plot experimental data to make the results
more universal. Some are also used in designing experiments to ensure dynamic similarity
between the flow of interest and the flow being studied in the laboratory.

8.1 Dimensionless Numbers
Dimensionless numbers or groups may be obtained from force ratios, by a dimensional
analysis using the Buckingham Pi theorem, for example, or by writing the differential equa-
tions of motion and energy in dimensionless form. Dynamic similarity between two geo-

Table 4 Coefficients of Contraction for Two-Dimensional
Jets