This spreadsheet is an Excel/VBA translation of a Fortran program from C.Y.Chow’s An Introduction to Computational Fluid Mechanics. The program tracks the motion of wingtip vortices and shows their motion as induced by each other and influenced by the nearby ground and the ambient crosswind. The user can change the crosswind speed, wingspan, mass and velocity of the aircraft and watch the impact on the subsequent motion of the vortices. The simple model includes no dissipation of the vortices, but it is well known that trailing vortices may be long-lived and dangerous to following aircraft.
The method of images is used to account for the presence of the ground.