Page 91 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition
P. 91
Total drag
Length to width/ diameter ratio
3.5 Design theory 79
FIGURE 3.16
Vehicle drag curves.
Ideal underwater body form after the scientists finish with it
Parallel mid-section after the procurement folks butcher it
FIGURE 3.17
Underwater vehicle body forms.
Skin friction drag
When considering the effect of the skin on the drag of the vehicle, the Reynolds number comes into play. Instead of starting with the technical description, let us take an example from the master himself—Theodore von Ka´rma´n:
Suppose that a book containing many pages is placed on a desk and the upper cover is slowly pushed parallel to the surface of the desk. The pages slide over each other, but the lower cover sticks to the desk. Similarly, fluid particles stick to the surface of a body, so that there is no slip between fluid and solid surface. Near the surface, however, the fluid velocity increases with the
Coefficient of drag
Form drag
Skin friction
