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7.1
SUBDIVISION OF THE BODY SURFACE IN PATCHES
AND PANELS
The body surface is first defined by one or more ‘patches’, each of which is a smooth
continuous surface in space. Contiguous patches meet at a common edge, where the coordinates are continuous but the slope may be discontinuous. A simple illustrative example
is provided by the circular cylinder of finite draft shown in Figure 7.1. (The same cylinder
is shown in Figure 6.1 as it would be represented by low-order panels.) Since there are two
planes of geometric symmetry we consider only one quadrant, represented by the shaded
portion of Figure 7.1. Two patches are used, one for the flat horizontal bottom and the
other for the curved cylindrical side. The important properties of the patches are that (a)
the surface is smooth, with continuous coordinates and slope, on each patch, and (b) the
ensemble of all patches represents the complete body surface (or one half or quarter of that
surface, if one or two planes of symmetry exist).
Figure 7.1: Representation of the circular cylinder by two patches on one quadrant, shown by the shaded
portion, with reflections about the two planes of symmetry.
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