A fast and robust viscous/inviscid interaction code for wing flowfield calculations

A fast analysis method for flow over wings is presented. A 3-D panel method has been combined with a 2-D viscous/inviscid interaction code which is used at multiple cross-sections across the wing span. Previously for a similar procedure, it has. been necessary to send data back and forth between the panel code and the boundary-layer solver.’ Now the boundary-layer is computed using Mark Drela’s XFOIL, which uses an improved, formulation for the boundary-layer edge velocity. It considers the total edge velocity as the sum of the inviscid solution and the viscous solution, where the inviscid result is totally independent of the viscous term. Therefore, there is no need to give any ’ information back to the 3-D panel code for repeated calculation, and this eliminates a significant computational effort. The background theory for both the 3-D panel method, and the 2-D flow solver is presented and the new combined method is described in detail. The calculation procedure for an arbitrary wing is presented. The new method is validated by comparing calculated pressure distributions and integrated results with experimental data and a Navier-Stokes solution. Good agreement with both is obtained. The new method is found to be fast and especially suitable for low Reynolds number flows.