Help for Moving Reference Frame.
 

I am doing a simulation on a drop rising in a tube. I chose Moving Reference Frame that is the frame is moving with the drop. I cannot find a proper criterion tell if it reaches a steady state or not. So my questions are:
(1)What should I pay more attention when using Moving Reference Frame? Maybe I got something wrong, so it never satisfy the criteria even the steady drop shape seems to be reached.
(2)I find the interface is much squiggly even I applied Savitzky-Golay smoothing filter several times. It is possibly part of reason the criteria cannot be satisfied. Any suggestions?
Many many thanks.