The fluid flow characteristics around any complex three-dimensional vehicle configurations such as an aircraft, automobile, etc., can be determined using the panel methods. The aerospace industry has pioneered in developing and adopting these methods which are ideal for comparatively easy surface modeling and analysis due to their time effective calculations. They show superior performance in modeling fully attached, high Reynolds number subsonic flows. Also, they are proficient in calculating the lift and form drag on the wing and/or over an entire aircraft as long as viscous effects are negligibly small. Although, the panel methods were originally conceived for incompressible flows \(\mathrm {\left( M<\text {0.3}\right) }\) only, however, by incorporating compressibility corrections they can be extended to high subsonic speeds \(\mathrm {\left( \text {0.3}<M<\text {1}\right) }\).

The panel methods are indeed powerful tools in analyzing the complex incompressible flow configurations, but they experience serious limitations in some situations. They are incapable of modeling the viscous effects, boundary layer characteristics and the phenomena where the flow separates. The lack of modeling the viscosity leads to further constraint; they cannot be used in modeling the forced vortices and/or rotational flows. The panel methods are incapable in modeling the flows at supersonic and hypersonic Mach numbers.