.. _physics-freefallTimeAvailable:

Freefall Time Available
=======================

Class providing models of the time available for freefall (in Gyr) in the cooling flow calculation, analogous to the cooling time available class but governing the freefall radius. This time, typically anchored to halo formation, enters the computation of the freefall radius and thereby determines which cooling regime applies. The rate of increase of this available time is also provided for use in ODE-based evolution of the hot gas atmosphere.

**Default implementation:** ``freefallTimeAvailableHaloFormation``

Methods
-------

``timeAvailable`` → ``double precision``
   Returns the time available for freefall in cooling calculations in ``node``.

   * ``type(treeNode), intent(inout) :: node``

``timeAvailableIncreaseRate`` → ``double precision``
   Returns the rate at which the time available for freefall in cooling calculations increases in ``node``.

   * ``type(treeNode), intent(inout) :: node``

.. _physics-freefallTimeAvailableHaloFormation:

``freefallTimeAvailableHaloFormation``
--------------------------------------

A freefall time available class in which the time available for freefall is equal to

.. math::

   t_\mathrm{available} = t - t_\mathrm{form},

where :math:`t_\mathrm{form}` is the time at which the halo formed (see Section ).

**(Default implementation)**