Failed FLIP FLUIDs and FLUID simulation

Hi, I’m trying to run a simulation to see how the geomorphology of certain caves can affect the flow of water. The data of the caves were obtained with a Lidar and processed in Matlab to then perform the surface reconstruction in meshlab and that cave was placed in blender. I am trying to make the water respect the laws of physics, but if I place the cave as a domain it makes it a square. And if I place a square surrounding the cave as a domain and the cave as an obstacle or Outflow, the water goes through it, all this using FLIP FLUIDS. And if I do it the other way using the fluid option of physical properties, where the cave is domain or effector and even the water does not respect the laws of physics. The cave is in OBJ format.

I am not sure if I have understood you correctly,
I would set the cave -geo as obstacle and probably also check inverse