The colors of these movie of temperaturs slices through the center of the stellar model are completely arbitrary: blue corresponds to about 2000 K (the outer atmosphere), green to about 3000 K (the photosphere), red to about 25000 K (layers just within the surface), and yellow to about 160000 K (the central temperature of the model). In the very core of a real supergiant the temperatures would increase to more than 100 Million K -- in a relatively small central region not included in the simulations.
This movie shows a temperature slice and "bubbles" that follow the flow.
For this movie "bubbles" have been superimposed
to the temperature to mark the actual flow of matter.
Cool (red) downdrafts with high convective velocities can transport matter
from the surface deep into the envelope.
In the outer atmosphere (blue) shock waves (green) are frequent.