In these movies, we place about 100,000 Lagrangian matter tracers that represent fluid elements. The initial distribution of Lagrangian tracers is proportional to the initial mass density. We then calculate the trajectories of the tracers by integrating the fluid velocities. The particles are also color-coded according to the density at their current location. These movies are displayed in static (ie. non-comoving) coordinates. Because of the large dynamic range in space using these coordinates, we pause in the middle of the animation to zoom up and see what happens near the center of the star. We zoom at the end as well to show what happens to the inner core of the star.
This view is particularly important because differential rotation is evident. In other words, the angular velocity is greater near the center than out in the lower density regions. The star is initially uniformly rotating but develops differential rotation as time passes.
Here we watch the same particles but from the equatorial plane.