frequency analysis using a moving fluid

Ruby,

try get the forces and apply them as a distributed load for frequency study.

Regards, Basil

Hi Rudy: You appear to be crossing into FSI territory, or "Fluid-Solid Interaction" capability, as touted by some competitors in CAE. If the flow field is transient in nature, (such as with vortex shedding), you would have to use that approach. However, by running a time-transient analysis in FloWorks, you might be able to observe a pressure "pattern" that repeats over some period, where you can identify the pressure field as a function of time. If the body being blown by the steam is not too affected by the flow (i.e., does not bend or move back and forth as a light pole bending in the wind), then it won't affect the flow field (that's a case to use true FSI software). So, if you could extract a pressure field around the surface as a function of time, you could apply that as an excitation load using COSMOSWorks Advanced Pro, Advanced Dynamics functionality. The software will use the system's natural frequencies (from a frequency analysis), and apply your pressure load over time to give you the structural response of the system. You want the structural deflection response to be small enough, in your judgment, not to affect the flow field for this entire approach to be valid, however. They key seems to be able to extract the pressure values, by surface coordinate, at each time step in the transient FloWorks analysis, over the recognized interval. Whew! I have not done that, but you would certainly be able to publish and charge for the method you develop! Tony

run a transient analysis and count the shedding frequency. I have done this for flow over a cylinder and it pretty much nails it relative to a hand calc using Strohal number.