Impeller > Meridional contour > Primary flow path > Hub, Shroud

A B-spline ("basis spline") is a collection of piecewise polynomial functions of a certain degree. The positions where the pieces of polynomial meet are known as knots. B-splines can be controlled by a number of control points and can handle complex smooth curves very flexibly.

The degree of B-Spline curves in CFturbo is limited to quadratic, cubic and quartic for more easy handling.

By using the context menu item "Insert knot", knots can be added at mouse cursor position, which can be considered as an internal split of the B-Spline curve to increase flexibility.