Abstract: A computing model with confluent boundary which computes the stall characteristics of multielement airfoils in a separated flow has been developed. A high order singularity panel method is used for the potential flow solution. The characteristics of ordinary and confluent boundary layer and viscous wake based on potential flow solution are obtained. A sparated wake model is used when the separation at the trailing edge of a certain element of the multielement airfoils occures. The final viscous solution is obtained by representing the boundary layer displacement thickness withan appropriate source distribution and by a viscous-potential interative technique. The calculated pressure distribution, the lift and the drag for angles of attack up to stall are in well agreements with experimental measurements.