  Powder-snow avalanches are violent natural disasters which represent a major
risk for infrastructures and populations in mountain regions. In this study we
present a novel model for the simulation of avalanches in the aerosol regime.
The second scope of this study is to get more insight into the interaction
process between an avalanche and a rigid obstacle. An incompressible model of
two miscible fluids can be successfully employed in this type of problems. We
allow for mass diffusion between two phases according to the Fick's law. The
governing equations are discretized with a contemporary fully implicit finite
volume scheme. The solver is able to deal with arbitrary density ratios.
Several numerical results are presented. Volume fraction, velocity and pressure
fields are presented and discussed. Finally we point out how this methodology
can be used for practical problems.
