# Loading due to an incident dilatational wave field

 Abaqus provides a capability for introducing generalized forces on acoustic and solid media associated with the arrival of dilatational waves. This capability applies to acoustic scattering problems and problems involving blast loads in air or water. Thus, the capability is available in transient dynamic procedures in Abaqus/Standard and Abaqus/Explicit. The following topics are discussed:
 Related Topics In Other Guides Acoustic and shock loads

ProductsAbaqus/StandardAbaqus/Explicit

Consider a dynamic problem involving fluid and coupled solid domains, excited by a propagating wave in the fluid arriving from outside these domains. When the mechanics of a fluid can be described as linear, wave fields in the fluid can be superimposed. Therefore, the observed total pressure in the fluid can be decomposed into two components: the incident wave itself, which is known, and the wave field excited in the fluid due to reflections at the fluid boundaries and interactions with the solid. To compute the latter, “scattered” solution, it is sufficient to apply loads at the boundaries of the fluid and solid domains corresponding to the effects of the incident wave field.

The fluid mechanical behavior is nonlinear when the fluid is capable of undergoing cavitation. In that case superposition of the incident wave and the response due to the boundaries, the solid, and the cavitating fluid regions to the incident wave loading is not valid. A total wave formulation (see Coupled acoustic-structural medium analysis) is used in Abaqus/Explicit to handle the incident wave loads on an acoustic medium capable of undergoing cavitation. In the total wave formulation the incident wave loading is applied as traction on the boundary of the modeled acoustic domain as the wave impinges on this domain from an external source. The default scattered wave formulation applicable in the absence of cavitation is presented below.