How to control fluid flow behavior after colliding with some effectors

Hi there,

I have a question regarding the flow behavior after it collided with some effectors.
I let fluid pouring into a tub. Then, there is an intended overflow of fluid and moste of the fluid should flow through the sink. The problem is, it does not go straight forward into the sink as you would imagine,

This marked fluid gets smashed pretty much directly into the direction of the sink.

But when it reached the ground, only a litte goes through the sink. Most of it goes alongside the sink, as if there would be a “magical wall”.

I am wondering why that is, because there is also a dip to the sink, so fluid should go there.

Any ideas what I could check?