Vortex lattice method

The vortex-lattice method models a lifting surface as a grid of horseshoe vortices, each a bound segment on the camber surface closed by trailing legs running downstream, with strengths set by enforcing flow tangency at panel control points. It extends lifting-line theory to surfaces of finite chord and sweep, and the Kutta condition is built into the trailing geometry. Lift follows from the bound circulation through the Kutta-Joukowski law and induced drag from the trailing-vortex downwash. In ship work it is a standard inviscid tool for propeller-blade and rudder loading and for foil and control-surface design before lifting-surface or RANS refinement.