We now assume the inclusion phase is a fluid so *K*_{i} = *K*_{f} and
*G*_{i} = *G*_{f} = 0. The fluid can be either a liquid or a gas.
We consider three cases: (1) liquid inclusion: ,(2) gas inclusion: ,(3) general inclusion: .Case 1 corresponds to liquid inclusions, Case 2 to gas inclusions,
and Case 3 to a circumstance in which crack aspect ratio is tuned to
fluid modulus, or in which we do not want to limit ourselves
to the assumptions of either of the previous two cases.

4/29/2001