The easiest way to do this is shown in the attached VI (7.0).
The trick can be understood when the cluster is enlarged - a customized slide was used where the image of the slider was replaced with the image of the flowing water (created very quickly in Word). Moving the image repeatedly creates the appearance of continuous flow. The credit for this trick, as far as I'm concerned, goes to JPD.
This can also be done using the picture control or maybe an intensity graph, but that would probably be more complicated.