Numerical study on multiple acoustic scattering by a vortex array.

In this paper, the multiple scattering features of acoustic waves by a vortex array are studied by numerical simulation through solving the two-dimensional Euler equations in the time domain with high-order-accurate finite-difference methods. The computations of scattered fields with a very small amplitude are found to be in excellent agreement with a benchmark provided by previous studies. A more physical vortex array model as the base flow for the problem of the multiple acoustic scattering is proposed and validated numerically. The influences of the spatial scales on the scattered fields are investigated, and the significant scattering is observed in the regime where the spatial scales of acoustic waves and vortical fields are comparable. Compared with single scattering, multiple scattering involves the interferences of scattered waves induced by each vortex of the array and shows more complexities. The most valuable observation is that the "zone of silence" arises behind the vortex array. A significant noise reduction of 10 decibels is achieved by using the optimized vortex array. • A more physical vortex array model as the base flow for the problem of the multiple acoustic scattering is developed and validated. • A method to measure the intensity of the interference field due to the multiple scattering is proposed. • The influences of the vortex strength, the length-scale ratio, and the direction angle on the interference fields are presented. • A significant noise reduction of 10 decibels is achieved by using the optimized vortex array. [ABSTRACT FROM AUTHOR]