Adiscretevortexmodelisdevelopedforsimulatingunsteadyseparatede owaroundanairfoilwithaconventional orbase-vented spoiler when the spoileris deployed ata e nitespeed. Theairfoiland spoilerarediscretized by linear segments. A linear distribution of vortices and a constant source are used to represent each segment, forming the basis of the present method. Discrete vortices are shed from each separation point. A new sharp-edge condition is formulated such that the location and strength of the nascent vortex near a separation point are determined by means of the continuity equation and the momentum principle. A method to model the moving surface is also presented. The no-slip condition and a diffusion scheme were incorporated into the numerical simulation for simulatingthee owaroundthebase-ventedspoiler.Thecomputedresultsarecomparedwiththoseofothermethods and with experimental results for the conventional spoiler. The computation of a base-vented spoiler shows that baseventing can reducetheadverseeffectwhenthespoilerundergoesrapid deployment.Thecomparison indicates that the present method provides reasonable results.