...
Initially, the shape of the front resembles a Gaussian, with a wide sloping surface and flat top. As the experiment progresses, the front frontal boundary gradually sinks relative to the free surface. Its sides flatten and the width of the center peak narrows.
...
Figure 4.4: azimuthal velocity as a function of radius for particles tracked at the surface of the front.
These particles are more different difficult to track, hence the tracks are shorter, and the concentration of dye and particles at the center of the front makes it impossible to track the particles for very small radii accurately. Still, it is clear from this plot that the azimuthal velocity of the fluid at the frontal surface has the same overall radial dependence as that of the fluid at the free surface. As expected, at for the same radiiradius, these particles have smaller azimuthal velocity than those at the surface. The Upon removal of the can, the fluid at the surface is displaced towards the center more than the fluid at lower depths is, therefore in order to preserve angular momentum the fluid at the surface fluid must acquire greater azimuthal velocity.
5 Challenge: Inverting the Dome!
...