Dear Lorenzo,
AeroDyn v12.58 and earlier had only one tower-influence model. This is a tower-shadow model that only creates a wake deficit behind the tower, so it only influences the aerodynamics of a rotor operating downwind of the tower.
AeroDyn v13.00.00-bjj has two tower-influence models. The default model is the same tower-shadow model from v12.58, as described above. The second tower-influence model includes a tower dam model for influence on an upwind rotor, as described in the AeroDyn Theory Manual: wind.nrel.gov/designcodes/simula … Theory.pdf.
AeroDyn v12.58 and earlier have only one tower-influence model. This is a tower-shadow model that only creates a wake deficit behind the tower, so it only influences the aerodynamics of a rotor operating downwind of the tower.
See the forum post found here for information on how the upwind tower-influence model can be enabled in your model: Tower shadow effect in FAST (1.5MW, test13).
I hope that helps.
Best regards,