Numerical analysis of the radiated fields of circular pistons andtime-delay spherically focused arrays

摘要

Radiated fields of a circular transducer and a time-delaynspherically focused transducer array are analyzed and compared usingnclassical impulse response method and finite element analysis. In thenfirst approach, the velocity potential at an observation point isnexpressed as the convolution of the excitation velocity and the impulsenresponse, while the pressure is obtained by the differentiation of thenvelocity potential. The impulse response for an array is expressed asnthe superposition of those of a series of circular pistons and isndependent on the observation point and piston/array structure. Thenfinite element method starts with the formulation for elastic waves, andnthe pressure fields are obtained through the pressure analog method. Nonparaxial or farfield approximation is needed and excellent agreement isnobserved between results from the two methods