Abstract
At intermediate Reynolds number, many equations which approximate drag coefficients for a sphere are collected in Table 1. These equations may be grouped in five formulas, and the errors between measured values and calculated values by means of these equations are shown in Fig. 1 to 5. When a sphere is accelerated, the mean errors of drag coefficients over initial and final Reynolds number are calculated and illustrated the equi-error diagrams as such “error contour” in Fig. 6 to 10.
