The Auto-select recommended models checkbox is ticked by default, which indicates that when there is a choice of models, the recommended model will be automatically selected. As an example of how this feature works, consider the continuum setup below, which indicates that a turbulent flow continuum is complete except for the choice of turbulence.
If you select K-Epsilon Turbulence, the Model Selection dialog will immediately appear as below, where two additional recommended models have been added:
The reason that these two models were all added after a single selection is that they are the recommended sub-models that were automatically selected.
If the Auto-select recommended models checkbox is cleared before K-Epsilon Turbulence is selected, the Model Selection dialog will appear as below. You now have to select among the choices of K-Epsilon Turbulence Models, and following that will have to select a wall treatment model and a wall distance model if required.
Therefore, if you want to select a model other than one that is recommended (say an alternative wall treatment model) there are two options: