Session Ce - Separated Flows.
ORAL session, Sunday, November 23
305, Moscone Center
The classical problem of discontinuous ideal flow consisting of potential streaming and a stagnation zone (Helmholtz problem) is treated numerically as a free boundary flow. Besides cylindrical coordinates, parabolic and quasi-parabolic coordinates are used which are topologically better suited to describe infinite stagnation zones.
Attention is focused on the case when the stagnation zone shrinks at infinity forming an infinitely-long cusp. Different flows past bluff bodies are considered: symmetric flows around cylinders, spheres and airfoils, as well as non-symmetric flows around NACA airfoils under a given angle of attack.
The result for the circular cylinder compares very well with the classical solution of Levi-Civita for the separated flow with zero drag. Within the truncation error the drag in the spherical case is also virtually equal to zero. The non-symmetric separated flows around airfoils obtained here exhibit nontrivial resultant forces whose components are the drag and lift force for the airfoils. The latter are in good quantitative agreement with the available experimental data for a variety of angles of attack.