The following main assumptions apply to the wall-film model:
The wall film thickness is thin and the wall film does not alter the geometry.
The existence of a wall film has no influence on the turbulence generation in the wall boundary layer.
Film particles are in direct contact to the wall and heat transfer from wall to film takes place by conduction.
Film particles originating from different particle types do not mix (that is, fuel droplets that hit oil-covered walls do not interact with each other). In Ansys CFX, the particle solver checks that only one particle type can form a wall film on a domain boundary.
In the non-flooded regime wall particles keep their spherical shape.
The simulation is assumed to be turbulent.
The wall film model can be used only in transient simulations.
The wall film model cannot be used together with dispersed Eulerian particles.