How do I make my normal always move down?

So i’m trying to make a water pooring effect by making a normal map pan down the mesh.
But it should always move down even when i rotate the mesh.
Now the normals are moving up and down left and right because I unwrapped the mesh and i’m just panning the normal map down the Y axis.

This should make it clear:

I will close this thread because you have a 2nd one with the same topic: Water pooring effect with normals problem - Rendering - Unreal Engine Forums :slight_smile: