Multiphase model G value and density issue

Hello everyone, I have some problem using the Reyleigh3D model. Could you help me a little bit about my problems.
Here is my input.
const T omega1 = 1.2;
const T omega2 = 0.58;
const int nx = 100;
const int ny = 100;
const int nz = 100;
const T G = 1.2;
The first question is that: I’m not really sure is that what is G value? is it a parameter to describe the interaction strength between two phases?
what is the range of it?

The second problem is that, I et density of two fluid as 0.8 and 1. However, after I run it around 2000 time steps, some part of the model has density shows as 2.3 and some part of the model has density as 0.02. it doesn’t make any sense. But the model runs well with fluid density 1 and 0.1. Can some one help me with it?