Abaqus - How to apply only a downwards pressure to a surface?

I am want to apply a vertical pressure to an organic surface. But because it is an organic surface, the forces won't be vertical and will be normal to face. If I were to apply a constraint to the top of the surface, saying it can only move in a vertical direction, U3, would this be considered downwards pressure?

Abaqus ​​​​​​​