### 6.8.1. Assumptions

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.

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