Grid Generator

The grid generator of FP sets up a computing grid in a transform space that consists of the interior of a unit length circular cylinder of unit radius, and computes all the transform derivatives and the coefficients of the flow equation that depend only on these derivatives. These transform derivatives and coefficients are utilised by the flow solver. The coordinates in the transformed space are (r,n,θ ), where n is the coordinate along the length of the circular cylinder, and r and θ are respectively the radial and azimuthal coordinates in the cylinder.

Configurations that may be dealt with are an isolated wing, also referred to as a 'wing-alone', and a wing-body combination, where the body is axially symmetric. The configurations are assumed to be symmetric about the plane y=0. Wing planforms may have straight or curved leading- and trailing-edges, and these edges may contain slope discontinuities (cranks). The body may be infinite or finite in length, but the grids employed are not sufficiently dense to enable finite body length effects to be treated accurately. The wing geometry is specified by a number of control sections in planes y = constant (up to 38 may be employed), together with corresponding twist (rotation) angles and centres of twist. The twisted sections are established and the wing geometry is interpolated between these. The form of interpolation may be selected by the user.