A comprehensive study of a modern acoustic technique is presented. The conservation laws of mass, momentum, and surface boundary conditions are cast in the form of an inhomogeneous wave equation, known today as Ffowcs Williams and Hawkings’ equation. The result is general, capable of addressing three-dimensional, nonlinear, and unsteady flow problems of compressible and viscous fluids. The Green’s function solution is used to transform the differential equation into integral form. The formulation is then linearized and viscosity is neglected. The pressure distribution on the surface of the NACA 0012 airfoil in subsonic non-lifting motion is determined. Comparison with experimental results shows good agreement, provided flow perturbations remain small. It is considered that the technique may evolve into an alternative aerodynamic method to current computational approaches.

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