Hello everyone! I am trying to use acoustic model in abaqus to model wave propagation by a point source. I tried to set inward volume acceleration as a constant value ,and the result had a very good agreement with analytic solution. Since there is little information related to this kind of boundary condition in Abaqus help document, I got confused with the concept of that. Could anyone tell me the general form of inward volume acceleration mathematically and what its physical meaning  is ?

Thank you so much!