Some aspects of three-dimensional separation. II - Vortex skeletons

A vortex-skeleton (VS) modeling technique for three-dimensional separated flows is developed and tested by means of the electromagnetic analogy. The VS method applies the Biot-Savart law to approximate the surface streamline patterns and flow topologies determined analytically using streamsurface bifurcations by Hornung and Perry (1984). Despite the simplifications involved, VSs are shown to reproduce the essential features observed in separated flows. The VS method is tested experimentally using the analogy between the velocity field around a potential line vortex and the magnetic field around a wire carrying a current (both of which obey the Biot-Savart law). The results are presented graphically in wiring diagrams, VS diagrams, and photographs of the magnetic-field lines. The flow configurations observed are classified, and four owl-face patterns are discussed in detail.