Drag Coefficients of Steel Spheres Entering Water Vertically

Drag coefficients have been determined from high speed motion pictures for ¼-inch to 1½-inch steel spheres shot into water vertically with speeds from 25 to 208 ft./sec. These drag coefficients correspond to the entrance cavity phase and to the v-squared-law drag forces only, the immediate effects on the spheres of other forces being eliminated in the calculations. It is found that CD is a function of both the Reynolds and Froude Numbers. Within the range investigated, the dependence may be expressed by CD=0.0174 ln(RF½).