Transformation Condition
One or several Transformation Condition subnodes can be added to a Phase Transformation node. In the Transformation Condition subnode, specify a Boolean expression c that has to be satisfied for the Phase Transformation to take place. For example, if you have reason to prevent a phase transformation from occurring unless the temperature rate is negative, the expression could look like:
metp.Tt<0[K/s]
If several Transformation Condition subnodes are used, each separate condition has to be satisfied for the Phase Transformation to take place.
In some situations, a Boolean expression c may be numerically challenging. It can be beneficial to use smoothed transformation condition. For example, a general Boolean expression a > b can be replaced by a smoothed Heaviside function as
flc1hs(2*(a-b)/h, 1)
causing c to increase smoothly from zero to one, across an interval of length h, centered at a = b.