Air Flow and Particle Trajectories around Aircraft Fuselages. IV: Orientation of Ice Crystals

Abstract

The equations of motion for an ice crystal moving around a body are simplified and used to obtain the preferred angular orientation of the crystals with respect to the body. It is shown that the calculated orientation angles are in good agreement with those measured by under-wing probes, and that the major cause of the preferential orientation of columns is the vortex generated at the tips of finite wings. It is also shown that a preferred orientation can be found in data obtained using fuselage-mounted probes, but there the agreement between the calculated and observed angles is not as good.