Annular time-domain acoustic source for horn acoustics
J. Agulló, Ana Barjau · The Journal of the Acoustical Society of America · 1998
The time-domain description of horns is needed in time-domain simulations of acoustical systems such as wind instruments and is very helpful to understand their transient behavior. Unidimensional horn wave equations have been used as a first approximation. The Webster horn equation, however, is too unrealistic for horns with intense flare. The improved horn equation developed by Keefe et al. [Proceedings of the SMAC-93 (1993), pp. 496–500] may be promising. A discretized approach that assumes the horn is made of cylindrical and conical elements with plane and spherical waves, respectively, has been widely used. More general alternatives based on the Kirchhoff integral are attractive because they can handle 2 and 3-D acoustic fields and lead to a surface discretization instead of volume discretization (as required in FEM). For axisymmetric horns, the use of an annular time-domain unit source, not implemented in commercial codes, dramatically reduces the number of elements. This paper presents the development of such a source and its application to time-domain horn acoustics. An example is presented for a cathenoidal horn and its results are compared to time-domain measurements.