High-speed method for computing the exact solution for the pressure variations in the nearfield of a baffled piston

A method is presented whereby the pressure variations at any point in the field of a baffled piston may be efficiently calculated. If a solution for the impulse response of a piston of a given geometry is known, then for harmonic excitation the steady-state field may be computed by evaluating the driving-frequency component of the Fourier transform of the impulse response. This method involves a single integration, whereas the direct numerical solution requires a double numerical integration. An exact, closed-form solution for the impulse response of a rectangular piston is derived. With this solution and the known solution for the impulse response of a circular piston the steady-state solutions for these two geometries are obtained. Three-dimensional and contour plots of data obtained for a circular piston and for a plane of symmetry of a rectangular piston field are presented. The plots for the circular piston compare favorably with previously published plots of data calculated by a double integration.