  This paper presents recent investigation results on free molecular flows over
a diffusely or specularly reflective ellipse, by using the gaskinetic theory. A
virtual density distribution along the a diffusely reflective surface is
introduced to aid the investigations. Many local surface properties are
obtained, including surface slip velocity, coefficients for pressure, friction,
and heat flux. Global coefficients for aerodynamic forces and moments, mass
center-force center distances, are also obtained by integrating the local
surface distributions. In the end, analytical expressions for the flowfields
around a diffusely or a specularly reflective ellipse are also obtained.
Special non-parameters, such as temperature and speed ratios, are explicitly
embedded in these expressions. Particle simulations with the direct simulation
Monte Carlo (DSMC) method are performed to validate the above results. Those
expressions need computers for evaluations, however, the cost is very minor
when compared with DSMC simulations. The approaches are heuristic to
investigate other external collisionless flows, and the load coefficients can
be considered as baseline references at the high Knudsen number limit. It is
feasible to further study less rarefied gas flows over an ellipse. Swift
parameter studies based on these solutions are feasible to study their
influences.
