droplet model using surface tension
 

After defining the velocity of a droplet in the void, it should fly along the certain direction and remain a sphere.

But when I use surface tension model simutaneously, it just flies for a short time and then breaks up.

During the flying period, the velocity changed both in direction and magnitude, and the volume of droplet decreased gradually.

Why did it happen? Is it resulted from the surface tension fluctuation solved by pressure iteration because of the droplet mesh movement?

Thanks!
(I have set all the other physic model off.)

It seems that the flying process can get steady if the speed is relatively large compared to the droplet size(mesh size).

If the speed is low, I can't get it stable even if giving a step-size small enough.

Can anyone help me?