CAESAR II does not address "acoustic analysis", which may be required here.

If the problem is "flow induced", then the only way you can approach the issue is with the "guessing game" I described above. This is not a trivial task, and if the response is not dominated by a single mode of vibration (natural frequency) you may never match the response of your actual system. In this case, an analysis by someone like Engineering Dynamics is a must.