Hi everybody,

does anybody has experience with modelling transient valve flow at steady state boundary conditions.

I have read a report about the simulation of a counterbalance valve where a jet flipping (a phenomena like vortex shedding behind a cylinder) occurs and was identified as the cause of high frequency (5 kHz), pure tone sound.

With the informations from the report i scanned the geometry of the model (2d axisymm) and set up a simulation with a finte element comercial code, but in my simulation there is no transient behaviour of the flow.

Does anybody done something similar or knows something about transient valve flow at steady state boundary conditions ?

I would be grateful for any help and suggestions

Can't comment on your valve problem as I have no experience.

The loss of transient behavior in a simulation (such as shedding, flapping, etc) can occur when the mesh resolution is inadequate. The numerical dissipation is so large that the simulation is run at an effective Reynolds number much lower than what is intended. Don't know if this is your problem or not - have you tried resolving your mesh and rerunning the problem?

it might also be worth checking to see if your finite element program does any sort of stabilization for flow programs, e.g. SUPG, GLS, etc... Under the right conditions such procedures can help prevent of the numerical diffusion that can occur with larger grid sizes.

Aaron