Plateau-Rayleigh
 

Hello,

I am trying to simulate classical Plateau-Rayleigh instability (breakup of falling liquid jet due to surface tension) in cfx. The materials are air and water. I am using homogenous multiphase model and standard free surface model, both materials are simulated as continous, surface tension is "continuum surface force", no mass or interphase momentum transfer. Air is basically just a filler.

Now, what is happening is that the radius of the jet becomes smaller as it falls, like it should be. But the shape of the jet is stable and it does not break up. I have tried both steady state and transient simulations.

The length of the jet is ~40x its largest radius. According to the theory for infinite jet, it is unstable for modes larger than its circumreference and the fastest growing mode is 9 times the radius.

Can anyone please advise? I am out of options :(