Fluid Structure Interaction involves the sciences of unsteady fluids as well as structural analysis.
In essence "Water Hammer" is influenced by the rigidity of the conduit that it occurs in. The conduits rigidity is not solely the pressure boundary itself, but "how" the conduit is constrained in space. The more rigid the conduit the faster sound travels within the fluid the greater the water hammer effect.
Thus the merge of two completely different applied sciences. Not for the timid or un-knowledgeable... to ask this particular question in a forum for a piece of software that is involved only in structural analysis of piping systems indicates that you are out of your depth of knowledge perhaps.
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Best Regards,
John C. Luf