Principle: vortex is a complicated 3-dimension current (it do both 2-dimension rotating in horizontal and moving up and down in vertical)shapes like a funnel, which has following features:
a、 it has an equal pressure upon every point in the cap surface of the funnel, thus is named constant pressure vortex surface.
b、 At the same level, the speed of water whirl has the inverse ratio with the radius; it flows with a high speed in areas with a small radius, which causes the pressure here low, And vice versa.
It has a high speed and low pressure in the center of the vortex, the more far from the center the more low speed and high pressure, which indicates that the vortex has a force of pushing toward the center. As a result, it is difficult for an object falling in vortex to escape.
Operation: the visitors fetch the small ball in the water and put it in the blowing machine. The ball falls into a barrel full of swirling water. After that, the visitors observe how the ball is absorbed in to the vortex.