Surface Tension

Surface tension can be calculated using 2 different models:

Gradient theory, see reference: 23

Linear gradient theory, see reference: 22

Influence parameter

The pure component influence parameter an be given by the use as a second order polynomial in temperature:

IP = a + b*T + c*T^2

This was done to given the user the flexibility to match pure component data that often does not follower a line

Lij

For the linear gradient theory the user can give a lij. The parameter is used in the mixing rule in the model and is similar to the kij used in most EOS.