  We develop a numerical method to study the dynamics of a two-component atomic
Fermi gas trapped inside a harmonic potential at temperature T well below the
Fermi temperature Tf. We examine the transition from the collisionless to the
collisional regime down to T=0.2 Tf and find good qualitative agreement with
the experiments of B. DeMarco and D.S. Jin [Phys. Rev. Lett. vol. 88, 040405
(2002)]. We demonstrate a twofold role of temperature on the collision rate and
on the efficiency of collisions. In particular we observe an hitherto
unreported effect, namely that the transition to hydrodynamic behavior is
shifted towards lower collision rates as temperature decreases.
