04j. Model Flow (Oscillating) Vibration - AutoPIPE

Comments, Questions, and Answers about modeling (Oscillating) Vibration in AutoPIPE:

Item #1:

In the calculation of pipe vibrations whether vibration of the pipe is taken into account or it's only gas-dynamic process?


Mechanical and Acoustic oscillations are considered uncoupled. That is AutoPIPE type vibrations do not cause more gas or liquid oscillations. The two analysis are done separately. For example, shaking forces from PULS are entered into AutoPIPE to calculate mechanical vibrations.

Item #2:

Pipeline has plug end. Will program calculate generation of self-oscillations in it or not?


Yes the program will generate response at dead ends as well, except that damping is assumed zero since no flow exists. Program can also evaluate cases of vortex shedding at closed tee branches.

Item #3:

Vortex Shedding - If you tell the program the flow rate and pressure, will AutoPIPE tell if the pipe will vibrate? Or will it handle any vibrational analysis. 


Jumpers are typically short sections of curved pipe spanning production riser elements on the sea floor. When in areas of significant currents these jumpers are subject to vortex induced vibration (VIV). The complex shape of the jumper means that numerical methods are usually needed to solve for the vibration modes of the jumper. Furthermore, the fluid flow around the jumper is also complex so that traditional methods of VIV analysis used for risers are not applicable to jumpers. .

As mentioned, this appears to be a vortex issue caused by flow on the outside of the pipe due to current. AutoPIPE does not have a way to analyze such vibrations at the moment.

SSD (ssdinc.com) have created a processor to process modal AutoPIPE results and process it for wind induced vibrations. The problem with this jumper appears more complex, due to special geometry and hence the need for CFD code solution.

PULS handles flow vortices inside the pipe caused by valve restrictions and closed tee branches.

See Also

Modeling Approaches in AutoPIPE

Bentley AutoPIPE