The effect of surface tension

plunger velocity = 80 cm/sec, aluminum, acceleration time = 0.1 sec

1. No surface tension

2. Surface tension = 670 dyne/cm

3. Surface tension = 3000 dyne/cm
 

The first simulation shows the flow pattern without surface tension
and the others show the effect of surface tension. Two values of surface tension are used for flow simulations
In the second one, 670 dyne/cm is used, because this value represent the surface tension of Al in a reducing gas environment, and In the last one, 3000 dyne/cm, because this value represents the surface tension of Al when an oxide layer gets formed on the surface.
As surface tension value increases, the wave created tend to come down to reduce the surface area.