Prediction of Subsonic Aerodynamic Characteristics: A Case for Low-Order Panel Methods

A low-order panel is presented for the calculation of subsonic aerodynamic characteristics of general configurations. The method is based on piecewise constant doublet and source singlarities. Two forms of the internal Dirichlet condition are discussed and the source distribution is determined by the external Neumann boundary condition. Calculations are compared with higher-order solutions fora number of cases. It is demonstrated that for comparable density of control points where the boundary conditions are satisfied, the low-order method gives comparable accuracy to the higher-order solutions. It is also shown that problems associated with some earlier low-order panel methods, e.g., leakage in internal flows and junctions and also poor trailing-edge solutions, do not appear for the present method. Further, the application of th Kutta conditon is extremely simple; no extra equation or trailing-edge velocity point is required