How does the multiphase model handle the wall contact of several phases?

[pitney1]

How does the multiphase model handle the wall contact of several phases? i.e. when an oil layer builds up on the wall, how is this phenomenon modeled and what stimulates further buildup of oil and controls the behavior of the layer in general?

[william]

 The behavior of the oil particles under various conditions is controlled by many factors including the chosen Drag model, i.e. Ishii-Zuber or some other model that might be applicable. The Ishii-Zuber drag model handles sparse and dense dispersed fluid (i.e. non-solid) particles automatically. Details of the Ishii-Zuber model can be found in the documentation: ANSYS CFX-Solver Theory Guide | Multiphase Flow Theory | Interphase Momentum Transfer Models |

For modeling of a change in flow behavior for dense packing conditions, using a drag model that provides a different calculation of the drag coefficient for different packing is essential.
The packing at the walls can be kept within reasonable limits by setting the maximum packing factor (default =1.0). This should prevent droplets from accumulating past an unrealistic packing value.

Other factors like flow field, surface finish, surface tension, etc. impact the behavior of fluid layers near walls.