Gas-Liquid flow
 

Hello,
I would like to simulate with OpenFoam the flow of magma (described as a mixture of an incompressible liquid and a compressible gas) in a volcanc conduit. The solver should be able to describe the exsolution of gas from the liquid phase, and eventually the "fragmentation": above a fixed threshold (for example the gas volume fraction exceed 0.75) the magma behaves like a gas+particles mixture and the viscous force acting on the liquid phase disappear or drastically reduces. The temperature can be considered quite constant during these processes. Can someone suggest me a solver, and eventually some tutorial, to start from?

Thank you
Mattia