Simple first order surface singularity methods based on:

• (i) Smith and Hess uniform source panels plus a uniform vorticity around aerofoil profile,

• (ii) piecewise linear vorticity around aerofoil profile, with different assumption for Kutta condition,

have been applied to attached flows and separated flows past an aerofoil/spoiler configuration, assuming an inviscid model.

For separated flows, piecewise linear vorticity methods give reasonable results as long as small panel elements are taken in the region of the separations at the spoiler tip and aerofoil trailing edge. The Smith and Hess method gives results which do not agree too closely with the vorticity methods. There is doubt concerning uniqueness.

Results have been compared using two different wake models; in one, the total head inside the wake is taken to be uniform, in the second, the static pressures along the separation streamlines are taken to be uniform. There appears to be a difference of about 5% in CL. It is not known why.